Methods for producing flexible ultraviolet light generation sheets and systems

ABSTRACT

Described are light generating devices employing ultraviolet (UV) light emitting diodes and one or more UV active materials, such as UV reflective materials, UV scattering materials, and UV transparent materials. A UV light generation system, may include a plurality of UV light emitting diodes arranged across a surface having a diffuse UV reflective layer. The UV light generation system may be arranged to enclose a fluid pathway or may be arranged as a liner of a container or vessel for use in disinfecting, purifying, or sterilizing fluid, particles or objects in the fluid pathway, container, or vessel by exposure of the fluid, particles or objects to UV light generated by the UV light emitting diodes.

TECHNICAL FIELD

The present invention relates generally to ultraviolet (UV) lightgenerating sheets and systems, and methods for making such sheets andsystems. More specifically, but not by way of limitation, the followingdescribes devices generating UV light and for treating, e.g.,disinfecting, fluids or materials by exposing the fluids or materials toUV light.

BACKGROUND

Exposure to UV light, corresponding to electromagnetic radiation withwavelengths of between about 100 nm and about 400 nm, is known to inducedegradation to many materials, including biological materials. UV lightcan break down DNA so that a cell cannot reproduce and can also degradetoxins, making UV light useful for disinfection or purificationpurposes. The use of UV light to kill pathogens, such as microorganisms,has found applications in disinfecting air, water, food, beverages, andblood components. UV disinfection has many advantages over alternativemethods, such as chlorine-based disinfection. For example, UV exposuredoes not introduce toxins or residues into the process and may not alterthe chemical composition, functionality, taste, odor, or pH of theproduct.

Traditional sources of UV light include mercury or xenon arc lamps.Mercury lamps, for example, may generate UV light with wavelengths of253.7 nm and 185 nm. More recently, UV light emitting diodes (LEDs) havebeen developed that offer the advantages of reduced power consumption,reduced size, longer lifetime, and instant turn on as compared totraditional mercury or xenon lamp sources. UV-LEDs may generate UV lightwith wavelengths from 200 nm to 400 nm, for example.

A typical UV treatment system includes an inlet port, a treatmentchamber in which air or water flows through the chamber, a UV lightsource that emits radiation that impinges the volume of the treatmentchamber, and an exit port. Due to their small size, however, toxins andpathogens can be shielded from UV light exposure, so improved UV lighttreatment systems and methods are useful.

U.S. Pat. No. 9,409,797 discloses a device for treating a medium usingUV radiation including a treatment chamber to accommodate the medium. AnLED UV radiation source provides UV radiation. A chamber-formingstructure has a stiffening base structure with at least one orificeformed therein and has a UV-radiation-transmissive film. The basestructure defines a placement of the UV-radiation transmissive film. Thechamber-forming structure separates the treatment chamber from the LEDUV radiation source, and the UV radiation is introduced into thetreatment chamber through the chamber-forming structure.

U.S. Pat. No. 9,586,838 discloses an LED-based system for purifying afluid flowing through a pipe, comprising means for mounting the systemon the pipe, a housing, a pliant carrier structure comprising aplurality of LEDs arranged flush with a first surface of the structureand configured to emit radiation in the UV range, wherein when thesystem is pipe-mounted, the structure is detachably arranged within thehousing, and the structure adopts a substantially tubular shape withinthe housing with the first surface delimiting a purifying chamber,wherein the purifying chamber is in fluid communication with the pipe sothat the fluid flowing through the pipe passes, prior to beingdispensed, through the purifying chamber where it is exposed to UVradiation of the energized LEDs.

U.S. Publication 2017/0281812 describes approaches for treating a fluidtransport conduit with ultraviolet radiation. A light guiding unit,operatively coupled to a set of ultraviolet radiation sources, enclosesthe fluid transport conduit. The light guiding unit directs ultravioletradiation emitted from the ultraviolet radiation sources to ultraviolettransparent sections on an outer surface of the fluid transport conduit.The emitted ultraviolet radiation passes through the ultraviolettransparent sections, penetrates the fluid transport conduit andirradiates the internal walls. A control unit adjusts a set of operatingparameters of the ultraviolet radiation sources as a function of theremoval of contaminants from the internal walls of the fluid transportconduit.

There continues to be a need for improved UV treatment systems.

SUMMARY

In the embodiments described herein, the present invention providestreatment, disinfection, or purification sheets and systems employingultraviolet (UV) light emitting diodes and one or more UV activematerials, such as UV reflective materials, UV scattering materials, andUV transparent materials, and methods of making UV light generationsheets and systems.

Disclosed UV light generation systems (also referred to as UV treatmentsystems and UV emitting systems) include those comprising flexiblecircuits featuring multiple UV-LEDs and, and other UV active layers,such as UV diffuse reflective layers or UV transmitting scatteringlayers. The UV light generation systems may also further includeadditional overlayers or underlayers, such as a supporting layer, a UVtransparent overlayer, or a UV transparent encapsulating layer. Thedisclosed UV light generation systems may be submersed in a fluid, suchas a liquid or a gas, and used to treat the material of the fluid orother materials suspended in the fluid, such as particles or objects, byexposure to UV light. The disclosed UV light generation systems may beflexible, allowing for their arrangement into enclosing configurations,such as configurations enclosing a fluid pathway. Optionally, thedisclosed UV light generation systems may feature wrappedconfigurations. For example, a UV light generation sheet may be arrangedin a helically wrapped configuration around a fluid path to allow fortreatment of fluid in the fluid path by exposure to UV light.Alternatively, UV diffuse reflective layers may be wrapped helicallywith gaps between longitudinal sides to allow for UV-LEDs to bepositioned at the gaps.

UV diffuse reflective or UV transmitting scattering layers of the UVlight generation systems may advantageously allow the transmitted UVlight to form an uniform UV light distribution, which may allow for moreeffective treatment and exposure to UV light, minimizing dim orunexposed areas in a treatment region. The UV diffuse reflective or UVtransmitting scattering layers may only minimally absorb UV light,allowing for high UV intensities to be generated with dispersal of thelight due to the diffuse reflective or scattering nature of the layers.The UV light generation system may also include photocatalysts, such asmetal oxides photocatalysts including titanium dioxide, on the surfaceof the overlayer that is exposed to the fluid medium. The use ofphotocatalysts that generate reactive oxygen species upon absorbing UVlight can be very effective in killing, destroying, or degradingpathogens.

Methods of making UV light generation systems include wrapping UVdiffuse reflective layers around a mandrel such that a gap is presentbetween adjacent, e.g., nearby, longitudinal sides of the UV diffusereflective layer and positioning a flexible circuit adjacent to the UVdiffuse reflective layer to align multiple UV-LEDs of a flexible circuitat the gap. A second UV diffuse reflective layer may be wrapped aroundthe mandrel and first diffuse reflective layer, such as in an oppositerotation direction, with a second gap that overlaps the first gap atmultiple locations corresponding to a plurality of openings. The methodcan further comprising positioning a flexible circuit including multipleUV-light emitting diodes (UV-LEDs) adjacent, e.g., adjoining, to thefirst or second UV diffuse reflective layer, wherein the positioning ofthe flexible circuit includes aligning the multiple UV-LEDs tocorrespond to the first gap or the openings when the second UV diffusereflective layer is used. The UV-LEDs of the flexible circuit may bealigned at the openings to allow light generated by the UV-LEDs to passthrough the openings. The first UV diffuse reflective layer may bewrapped around an overlayer, e.g., an overlayer comprising aphotocatalysts, such as titanium dioxide (TiO₂).

In one embodiment, there is provided a method of making an ultraviolet(UV) light generation system, the method comprising wrapping a first UVdiffuse reflective layer in a first direction around a mandrel with afirst gap between adjacent, e.g., nearby, longitudinal sides of thefirst UV diffuse reflective layer, wherein the first UV diffusereflective layer is flexible, and positioning a flexible circuitincluding multiple UV-light emitting diodes (UV-LEDs) adjacent, e.g.adjoining, to the first UV diffuse reflective layer, wherein thepositioning of the flexible circuit includes aligning the multipleUV-LEDs to correspond to the first gap. The flexible circuit may bealigned with the multiple UV-LEDs to correspond to the first gap. Eachof the multiple UV-LEDs is positioned to direct generated UV lightthrough the first gap.

In another embodiment, there is provided a method of making anultraviolet (UV) light generation system, the method comprising wrappinga first UV diffuse reflective layer in a first direction around amandrel with a first gap between adjacent longitudinal sides of thefirst UV diffuse reflective layer, wherein the first UV diffusereflective layer is flexible, wrapping a second UV diffuse reflectivelayer in a second direction around the mandrel and the first UV diffusereflective layer with a second gap between adjacent longitudinal sidesof the second UV diffuse reflective layer, wherein the second UV diffusereflective layer is flexible, and wherein a portion of the first gap anda portion of the second gap overlap to generate a plurality of openings,positioning a flexible circuit including multiple UV-light emittingdiodes (UV-LEDs) adjacent to the second UV diffuse reflective layer,wherein the positioning of the flexible circuit includes aligning themultiple UV-LEDs to correspond to the plurality openings. Each of themultiple UV-LEDs is positioned to direct generated UV light through theopenings.

Other methods of making UV light generation system, such as a UV lightgeneration sheet, are disclosed, Such methods may comprise generating aplurality of openings in a UV diffuse reflective layer and positioning aflexible circuit adjacent to the UV diffuse reflective layer such thatmultiple UV-LEDs of the flexible circuit are aligned at the openings.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic illustration showing a cross-section of aflexible UV light generation sheet in accordance with some embodiments.

FIG. 2A and FIG. 2B provide schematic illustrations showingcross-section side and overhead views of flexible UV light generationsheets in accordance with some embodiments.

FIG. 3A and FIG. 3B provide schematic illustrations showingcross-sections of flexible UV light generation sheets in accordance withsome embodiments.

FIG. 4 provides a schematic illustration showing a cross-section of aflexible UV light generation sheet in accordance with some embodiments.

FIG. 5 provides a schematic illustration showing a cross-section of aflexible UV light generation sheet in accordance with some embodiments.

FIG. 6 provides a schematic illustration showing a cross-section of aflexible UV light generation sheet in accordance with some embodiments.

FIG. 7A and FIG. 7B provide schematic illustrations showingcross-sections of flexible UV light generation sheets in accordance withsome embodiments.

FIG. 8A and FIG. 8B provides a schematic illustration showing a flexibleUV light generation sheet arranged in a helical wrapped configuration inaccordance with some embodiments.

FIG. 8C provides a schematic illustration showing a flexible UV lightgeneration sheet arranged in a longitudinal wrapped configuration inaccordance with some embodiments.

FIG. 9A and FIG. 9B provide a schematic illustrations showingcross-sectional views of UV treatment systems in accordance with someembodiments.

FIG. 10 provides a schematic illustration showing a cross-sectional viewof a UV treatment system in accordance with some embodiments.

FIG. 11 provides a schematic illustration showing a cross-sectional viewof a UV treatment system in accordance with some embodiments.

FIG. 12 provides a schematic illustration showing a cross-sectional viewof a UV treatment system in accordance with some embodiments.

FIG. 13A and FIG. 13B provides schematic illustrations showingcross-sectional and side views of a UV treatment system in accordancewith some embodiments.

FIG. 14 provides an example circuit for driving LEDs in a seriesconfiguration.

FIG. 15 provides an example circuit for driving LEDs in a parallelconfiguration.

FIG. 16 provides an example circuit for driving LEDs and monitoring UVlight output using a UV sensitive photodetector.

FIGS. 17A-17F provide schematic illustrations (front (1), side (2), andtop (3)) detailing a method of making a UV light generation system inaccordance with some embodiments.

FIG. 18 provides a plot showing total reflectivity of a UV diffusereflective layer as a function of wavelength.

FIG. 19 provides a plot showing total transmission of differentmaterials as a function of wavelength.

FIG. 20 provides a plot showing haze percent of different materials as afunction of wavelength.

FIG. 21 provides an overview of an example method of making a UV lightgeneration system in accordance with some embodiments.

FIG. 22 provides an overview of an example method of making a UV lightgeneration system in accordance with some embodiments.

FIG. 23 provides an overview of an example method of making a UV lightgeneration system in accordance with some embodiments.

FIGS. 24A-24F provide schematic illustrations of methods of making a UVlight generation system using one UV diffuse reflective layer inaccordance with some embodiments.

FIGS. 25A-25F provide schematic illustrations of methods of making a UVlight generation system using two UV diffuse reflective layers inaccordance with some embodiments.

FIGS. 26A and 26B provide schematic illustrations of methods of making aUV light generation system using one UV diffuse reflective layer and onetransparent overlayer in accordance with some embodiments.

DETAILED DESCRIPTION

The present invention provides various embodiments of a flexible UVlight generation system or assembly that includes a plurality of UV-LEDsarranged across a surface area of the flexible UV light generation sheetor assembly. It will be appreciated that the disclosed UV lightgeneration systems are useful in disinfection, sterilization,purification, and other treatment applications. The disclosed flexibleUV light generation sheets and assemblies are useful as part of or toconstruct a UV treatment systems or UV light generation systems. Thearrangement on the surface area achieves a wide distribution, and in oneembodiment an uniform distribution, of the UV emission field bytransmissively scattering and/or diffusely reflecting the UV light. Theinventors have found that a uniform distribution is more advantageous indisinfection, purification, and sterilization systems because void ordark areas are reduced or may be eliminated. For example, a dark areacould allow an impurity or pathogen to pass through without beingdisinfected, purified, sterilized, or otherwise treated.

Example flexible UV light generation systems include those comprising aflexible circuit having multiple UV-LEDs. The flexible circuit mayinclude a plurality of conductors, with each UV-LED positioned inindependent electrical communication with at least one of the pluralityof conductors. It will be appreciated that the multiple UV-LEDs may bearranged as an array and that the term array, as used herein, maycorrespond to a spatial distribution of a plurality of objects, such asUV-LEDs and conductors, with one or more of the objects connected toand/or attached to other objects in the array, such as by electricalconnections. An array may be regular or non-regular, meaning the objectsmay be uniformly distributed or non-uniformly distributed. An examplearray may correspond to a ribbon cable, flexible circuit, or flatflexible cable having UV-LEDs attached along various positions of theribbon cable, flexible circuit, or flat flexible cable.

The flexible circuit may be flexible and supported or otherwise attachedto another flexible layer, such as a flexible UV diffuse reflectivelayer or a flexible UV transmissive scattering layer. In someembodiments that include a UV diffuse reflective layer, the UV diffusereflective layer may include a plurality of openings, arranged toposition each opening adjacent to a corresponding UV-LED, such that thecorresponding UV-LED is exposed through the opening to allow UV lightgenerated by the corresponding UV-LED to pass through the opening.

In one embodiment to achieve an uniform distribution, the UV lightgeneration system is arranged to position at least a first UV-LED of themultiple UV-LEDs in a configuration that is directly opposed to a UVdiffuse reflecting layer, such as a highly diffuse UV reflecting layer.In one embodiment to achieve an uniform distribution, the UV lightgeneration system is arranged to position at least a first UV-LED of themultiple UV-LEDs in a configuration that is not directly opposed to anyother of the multiple UV-LEDs. In one embodiment to achieve an uniformdistribution, the UV light generation system includes a UV transmissivescattering layer or overlayer, such as a high haze film, to scatter ordefocus UV light generated by the UV-LEDs. Optionally, these embodimentsmay be combined to provide advantageous positioning of UV-LEDs andinclusion of a UV transmissive scattering layer. In one embodiment, theUV transmissive scattering overlayer does not include UV absorbingfiller material.

The stream being treated may be a gas or liquid stream that containsimpurities such as pathogens, toxins, particulates, and combinationsthereof. Treatment may be useful for reducing the impurities, orpreferably eliminating the impurities, to produce a clean stream bydisinfection, purifying, or sterilization. In one embodiment a liquidstream, such as water, blood, milk, or oil, is treated for use insensitive applications that require high purity. In another embodiment,a gas stream is treated for use in sensitive applications that requirehigh purity. In another embodiment, a gas stream comprising solidparticles, such as food stuffs or seeds, is treated to disinfect,purify, or sterilize impurities. The gas stream may contain air ornitrogen and concentration of solid particles may vary from 0.1 to 99.9%in the gas stream. It should be understood that the impurities may beless than the solid particles.

A UV light generation sheet may have a width and a length that are ofthe same or similar dimensions in a generally rectangular configuration.A flexible UV light generation sheet may alternatively be constructed asa ribbon or tape, such as a rectangular configuration in which a widthis considerably smaller than a length, such as where the length is 5times greater (or more) than the width. Other sheet shapes are possible,such as circular, oval, and polygonal, as well as any other conceivableshape that may be constructed from a web of material.

A UV light generation sheet or system may optionally be flexible,allowing arrangement of the UV light generation sheet or system todefine a fluid pathway, for example. To achieve flexibility, associatedcomponents of the UV light generation sheet or system may be flexible.As an example, a UV diffuse reflective layer, underlayer, or overlayermay optionally be flexible. As another example, a UV transmissivescattering layer, underlayer, or overlayer may optionally be flexible.In one embodiment, to define the fluid pathway the UV light generationsheet or system is wrapped, such as helically wrapped, laterallywrapped, or otherwise circumferentially arranged around the fluidpathway. The wrapped UV light generation sheet or system may form atubular shape that corresponds to the fluid pathway. UV light generationsheet or system embodiments may be wrapped in a non-overlapping oroverlapping configuration. In other embodiments, one or more UV lightgeneration sheets or systems may be helically wrapped to define a fluidpathway. Any desirable configuration may be used herein, such as aplanar configuration, a convex configuration, a concave configuration,and combinations of these.

Materials in UV light generation sheets and systems may individuallyand/or collectively have elastic, compressive, or bending modulisuitable for the overall structure to be flexible. Example elastic,compressive, or bending moduli for flexible assemblies and materialsexhibit an elastic modulus of between 0.001 GPa and 3.0 GPa. In someembodiments, materials included in a UV light generation sheet or systemmay exhibit an elastic, compressive, or bending modulus outside of thisrange. For example, conductors used for providing current and/or voltageto one or more UV LEDs may have a relatively larger elastic modulus, butmay still exhibit flexibility along one or more axes, such as by way ofa suitable bending modulus or compressive modulus, sufficient forinclusion in a flexible assembly. In general, the term flexible refersto materials that elastically bend in response to a force rather thanfracture or undergo inelastic deformation, and the term flexible may beused interchangeably herein with the terms pliable and bendable. In someembodiments, flexible materials may be bent to a radius of curvature of1 cm or less (e.g., 1 mm to 1 cm) without undergoing fracture orinelastic deformation. Various ASTM and ISO standards are useful fordetermining or specifying flexibility features of different materialsincluding ASTM standards D747, D790, D5045, D7264, E111, E1290, E1820,and E2769 and ISO standards 170, 178, 12135, and 12737, which are herebyincorporated by reference.

Example configurations include a tube-like configuration, where theflexible UV light generation sheet or system is arranged to enclose aninterior space, such as by wrapping the flexible UV light generationsheet or system around a hollow or solid tube or other cylindricalstructure, such as a mandrel. Depending on the configuration, UV lightgenerated by the UV-LEDs may be directed into the interior space oropposite to the interior space. Other configurations useful with someembodiments, include pouch-like configurations where two portions orsections of a flexible UV light generation sheet or system are placedadjacent to one another such that material or fluid may be insertedbetween the two portions or sections. In some embodiments, one or moreflexible UV light generation sheets or systems may be arranged as aliner of a vessel or container and used to generate UV light within theinterior space of the vessel or container.

It will be appreciated that the flexible UV light generation sheet orsystem does not need to completely enclose an interior space. Forexample, in some embodiments, the vanes in a static mixer or one outerwall may be covered with a flexible UV light generation sheet or system.In another embodiment, the enclosed space may not be defined. Forexample, a flexible UV light generation sheet or system could be mountedone end with the opposite end free to move in a fluid stream, similar toa flag. The flag configuration may use or correspond to a flexible UVlight generation sheet that has UV-LEDs mounted on one side or bothsides.

FIG. 1 provides a schematic cross-sectional side-view illustration of aflexible UV light generation sheet 100 in accordance with someembodiments. A UV-LED 150 is electrically connected to individualsegments of conductor 110 to allow current to be applied for UV lightgeneration. Below conductor 110 is a support layer 130 and aboveconductor 110 is a UV diffuse reflective layer 120. Support layer 130may optionally be one or more UV diffuse reflective layers. UV diffusereflective layer 120 is positioned so light from UV-LED 150 can beemitted out of flexible UV light generation sheet 100. Support layer 130is positioned below UV-LED 150 and may also be UV reflective such thatstray light is reflected back. Openings 140 may be included in UVdiffuse reflective adjacent layer 120 to allow light from the UV-LED 150to be emitted there through. The openings 140 may have a variety ofshapes including circles, ovals, triangles, squares, rectangles,diamonds, and other similar shapes. The size of the opening may alsovary but is sufficient to allow light from a UV-LED 150 to pass throughand may have an opening size from 0.5 to 20 mm, e.g. from 2 to 10 mm, orfrom 3 to 6 mm. In one embodiment, the openings 140 may be formed bygaps created between adjacent longitudinal sides of one or more UVdiffuse reflective layers that are wrapped to form the sheet.Optionally, conductor 110 may be segmented, such as at openings 140, toallow different contacts of electrical components to be attached to theindividual segments.

As illustrated, a lens or focusing element is not positioned aboveUV-LED 150. When no lens or focusing element is used, the configurationadvantageously permits UV light intensity to spread over a wider areaand achieve a more uniform distribution of UV light intensity over awider area, minimizing dim regions that may occur when lensing orfocusing elements are included.

FIG. 2A provides a schematic cross-sectional end-view illustration andFIG. 2B provides a cross-sectional top-view illustration of a flexibleUV light generation sheet 200 in accordance with some embodiments. FIG.2A shows a flexible UV light generation sheet 200 in which conductors210 are optionally included in a ribbon or a flexible flat cable and maybe joined or attached to one another by way of electrically insulatingmaterial surrounding at least a portion of one or more conductors. UVdiffuse reflective layer 220 may be positioned above conductors 210,such that UV diffuse reflective layer 220 covers at least a portion ofconductors 210 and/or any insulating material surrounding theconductors. It will be appreciated that UV diffuse reflective layer 220may be in individual sections positioned above each conductor 210 or maya continuous layer positioned above any number of conductors 210.Support layer 230 may be positioned below the conductors 210, and belowUV-LEDs 250, such that support layer 230 covers at least a portion ofthe conductors 210 and UV-LEDs 250 and/or any insulating materialsurrounding the conductors and UV-LEDs. Optionally, support layer 230 isa UV diffuse reflective layer. It will be appreciated that support layer230 may be in individual sections positioned below each conductor 210 ormay a continuous layer positioned below any number of conductors 210 andUV-LEDs 250. It will be appreciated that a support layer may be anoptional feature of the flexible UV light generation sheets describedherein, as the structure of the UV-LEDs, conductors, a UV transparentscattering or UV diffuse reflective layer, and any additional layers,such as overlayers, may provide sufficient structure to the flexible UVlight generation sheet such that a separate support layer is not needed.Optionally, UV diffuse reflective layer 220 or support layer 230 may beprovided as a jacketing material of conductors 210.

FIG. 2B may correspond to a perpendicular view from those shown in FIG.1 and FIG. 2A. In flexible UV light generation sheet 200, conductors 210are included and shown extending from edges of flexible UV lightgeneration sheet 200. Conductors 210 are at least partially covered by aUV diffuse reflective layer 220. UV-LEDs 250 are illustrated aspositioned above several conductors 210, with an additional conductor210 used as a common or current return line. Similar to FIG. 1, UV-LEDs250 may be positioned at openings in UV diffuse reflective layer 220 andbridging segments of conductors 210. It will be appreciated that, asillustrated in FIG. 2B, UV-LEDs 250 may be individually electricallyaddressable. Allowing the UV-LEDs to be individually electricallyaddressable may provide good control to adjust the UV light within thefluid pathway to achieve an uniform UV emission. It will be appreciatedthat FIGS. 2A and 2B provide an array of multiple UV-LEDs 250 with aplurality of conductors 210, such as a non-regular array.

As an alternative to driving LEDs in series with a common current, LEDsmay be driven in parallel with a common voltage. FIG. 3A provides across-sectional schematic illustration of a flexible UV light generationsheet 300 including a ribbon cable. The ribbon cable includes aplurality of round conductors 310, each depicted as a stranded corecable. It will be appreciated that solid core conductors are alsouseful. A UV-LED 350 is depicted as positioned adjacent to and inelectrical communication with two different conductors, in contrast tothe configuration illustrated in FIGS. 1, 2A, and 2B, where a UV-LED ispositioned to bridge segments of a single conductor. FIG. 3B provides across-sectional schematic illustration of a flexible UV light generationsheet 300 where one conductor, for example the center conductor, may beused as a heat sink, for example, to allow heat generated by one or moreUV-LEDs to flow away from the UV-LEDs.

FIG. 4 provides a cross-sectional schematic illustration of a flexibleUV light generation sheet 400 including a ribbon cable with a pluralityof conductors 410, UV-LEDs 450 and adjacent layer 420. An additionaloverlayer 460 is depicted as positioned above UV diffuse reflectivelayer 420 and above UV-LEDs 450. Overlayer 460 is a UV transparentlayer, allowing UV light generated by UV-LEDs 450 to transmit out fromflexible UV light generation sheet 400. In addition, incident UV lightmay transmit through overlayer 460 and be reflected by adjacent layer420 back through overlayer 460 and into the medium above the flexible UVlight generating sheet 400. Optionally, additional overlayer 460 may bea UV transmissive scattering layer, allowing UV light generated byUV-LEDs 450 to transmit out from flexible UV light generation sheet 400and be scattered to more uniformly distribute the light. A UVtransmissive scattering layer, also referred to as a UV haze layer or UVtransmissive scattering layer, diffuses light over a wide range ofangles. ASTM standard D1003, hereby incorporated by reference, describesdetails of haze and transparency measurements, and defines haze as theratio of diffuse transmittance to total luminous transmittance, whichmay correspond to the percentage of light passing through a layer thatdeviates from the incident beam greater than 2.5 degrees on average.Optionally, overlayer 460 may correspond to an encapsulating layer,which may provide water resistance or other environmental protection tounderlying components. Advantageous properties of an overlayer mayinclude electrically insulation, low water and oxygen transmissionrates, high mechanical toughness, and high thermal conductivity.Optionally a UV diffuse reflective underlayer 430 is positioned belowthe UV-LEDs to redirect any backward scattered light in the forwarddirection above the UV-LEDs. In this embodiment, little if any light islost and less power is required to disinfect the fluid stream.

FIG. 5 provides an alternative embodiment of a flexible UV lightgeneration sheet 500 including a ribbon cable with a plurality ofconductors 510 and UV-LEDs 550. FIG. 5 is similar to FIG. 4 except thatthe overlayer 560 is below adjacent reflector layer 520. FIG. 6 providesa further alternative embodiment of a flexible UV light generation sheetsimilar to FIG. 4 and FIG. 5 except that the adjacent reflective layer520 has been removed. In this embodiment, incident light would transmitthrough the overlayer 660 and be reflected by underlayer 630.

In some embodiments, a flexible UV light generation sheet makes use of aflexible circuit rather than a ribbon or flat flexible cable forproviding electrical connections to one or more UV-LEDs. For example,FIG. 7A provides a schematic cross-sectional illustration of a flexiblecircuit-based UV light generation sheet 700. Here, flexible UV lightgeneration sheet 700 includes flexible circuit 715, which corresponds,for example to a flexible conductive trace 712 supported on a flexiblesubstrate film 714. As an example, flexible conductive trace 712 maycorrespond to a thin copper layer and flexible film 714 may correspondto a polymer film, such as polyimide. UV-LEDs 750 may be positioned inelectrical communication with portions of flexible conductive trace 712and supported by flexible film 714. An overlayer 760, such as a UVtransparent layer or a UV transmissive scattering layer, may beincluded, depending on the particular configuration. The overlayer 760may protect the UV-LEDs from the environment including, for example,immersion in water. Advantageous properties may include electricallyinsulation, low water and oxygen transmission rates, high mechanicaltoughness, and high thermal conductivity. A reflective underlayer 730,and a reflective layer 720, may be included, depending on the particularconfiguration.

Another embodiment depicting a flexible UV light generation sheet 700using a flexible circuit rather than a ribbon or flat flexible cable isshown in FIG. 7B. Here, flexible UV light generation sheet 700 includesflexible circuit 715, which corresponds, for example to a flexibleconductive trace 712 supported on a flexible film 714. As an example,flexible conductive trace 712 may correspond to a thin copper layer andflexible film 714 may correspond to a polymer film, such as polyimide.UV-LEDs 750 may be positioned in electrical communication with portionsof flexible conductive trace 712 and supported by flexible film 714.Openings may be included in in flexible film 714, to allow UV lightgenerated by UV-LEDs 750 to be transmitted away from flexible UV lightgeneration sheet 700. Alternatively, flexible film 714 may betransparent to the emitted light from UV-LEDs so openings are notrequired. A reflective underlayer 730, and a reflective layer 720, maybe included, depending on the particular configuration.

UV Light Generation Assembly Configurations

A variety of UV light generation systems using the flexible UV lightgeneration sheets described herein are contemplated. As an example, FIG.8A depicts a UV light generation system 800A including a flexible UVlight generation sheet 805 wrapped in a helical configuration around atubular structure 815. In one embodiment, the UV light generation sheet805 has opposing longitudinal sides that are adjacent or partiallyoverlap. The tubular shape may correspond to the fluid path 825. In thisway, flexible UV light generation sheet may be arranged to enclose afluid path 825, corresponding to an interior region of tubular structure815, for example. The fluid path 825 may be useful for flowing liquidsor gases through a region illuminated by UV light for disinfecting orpurifying the liquids or gases. Optionally, particles or objects may besuspended in the fluid and exposed to the UV light for disinfecting orpurifying the particles or objects. Optionally, flexible UV lightgeneration sheet 805 and tubular structure 815 are flexible, allowingtreatment system 800A to adopt a bent or curved configuration.Optionally, tubular structure 815 is a mandrel used to form a tubularshape when the flexible UV light generation sheet is wrapped. In thisembodiment, the mandrel is removed to form a fluid pathway. Inembodiments, tubular structure 815 is a UV transparent tube, permittingUV light generated by UV-LEDs of flexible UV light generation sheet 805to transmit into an interior of tubular structure 815. In thisembodiment, the UV transparent tube may be considered part of the UVlight generation system. In one embodiment, UV-LEDs of flexible UV lightgeneration sheet 805 are arranged to position at least a first UV-LED ina configuration that is not directly opposed, across the fluid path 825,to any other UV-LED. Incidentally, UV-LEDs of flexible UV lightgeneration sheet 805 are arranged to position at least a first UV-LED ina configuration that is directly opposed, across the fluid path 825, toa UV diffuse reflective layer of flexible UV light generation sheet 805.This allows the UV light to reflect and become more uniformlydistributed in the fluid pathway. In FIG. 8A, conductors 810 are alsoillustrated as extending from flexible UV light generation sheet 805 andmay be connected to circuits or power sources. It will be appreciatedthat for direction of UV light into fluid path 825, UV-LEDs will bepositioned facing tubular structure 815. UV-LEDs are on the side of thesheet facing the interior and are not visible from the exterior as shownin FIG. 8A.

FIG. 8B is a perspective view to show the interior region of the UVlight generation sheet 805. For purposes of illustration the tubularstructure 815 is not shown in FIG. 8B. The UV light generation sheet 805has openings 840 that align with UV-LEDs 850 on the conductors (notshown in FIG. 8B). The UV light generation sheet 805 may be constructedof a diffuse UV reflective layer 820. It will be appreciated thatadditional overlayers or underlayers may optionally be included in UVlight generation sheet 805, e.g., such as a reinforcing underlayer, a UVtransparent overlayer, and/or a UV transmissive scattering overlayer. Inone embodiment, the UV transparent overlayer has a UV transmission of atleast 80% at 250 nm. As shown in FIGS. 8A and 8B, the sheet 805 iswrapped closely together and may partially overlap to prevent a gapbetween the adjacent longitudinal sides.

Optionally, a surface at the fluid pathway may be coated with or treatedwith TiO₂ or another UV active photocatalytic material. Otherphotocatalytic materials include metal oxides such as SiO₂, ZnO, Bi₂WO₆,Bi₂OTi₂O, Fe₂O₃, Nb₂O₅, BiTiO₃, SrTiO₃, or ZnWO₄, and other metalcatalysts such as CuS, ZnS, WO₃, or Ag₂CO₃. Upon exposing TiO₂ oranother light active photocatalytic material UV light generated by LEDs,electrons and holes may be generated to allow oxidation and/or reductionof material coming into contact with the TiO₂ or active photocatalyticmaterial. For example, contacting a light activated photocatalyst withwater or oxygen may result in generation of reactive oxygen species,such as hydroxyl radicals (OH) and superoxide (O₂ ⁻ ). These reactiveoxygen species may be useful for degrading or destroying pathogens,toxins, or impurities.

An alternative arrangement of a UV light generation treatment system800B including flexible UV light generation sheet 805 is depicted inFIG. 8C, where instead of being helically wrapped around the fluid path825, the flexible UV light generation sheet 805 is longitudinallywrapped around the fluid path 825. It will be appreciated that in theillustration depicted in FIG. 8C the longitudinal wrap around fluid path825 is shown as incomplete for purposes of illustration. In practice,ends of flexible UV light generation sheet 805 may optionally beattached and/or joined to form a complete enclosed fluid path 825. Thisprevents a gap between the sides of the sheet 805 in FIG. 8C. In FIG.8C, conductors 810 are also illustrated as extending from flexible UVlight generation sheet 805. There are various openings 840 in the UVlight generation sheet 805 that are positioned to align with the UV-LEDs850 connected to the conductors 810. It will be appreciated thatadditional overlayers or underlayers may optionally be included in UVlight generation sheet 805, e.g., such as a reinforcing underlayer, a UVtransparent overlayer, and/or a UV transmissive scattering overlayer. Inaddition, the UV light generation sheet 805 shown in FIG. 8C may bewrapped around a transparent tube.

FIGS. 9A and 9B depict schematic cross-sectionals illustration of UVlight generation systems 900A and 900B, such as using the flexible UVlight generation sheet depicted in FIG. 5, including UV diffusereflective layer 920, underlayer 930, UV-LEDs 950, flex circuit 915 andoverlayer 960, which may be positioned in various adjacencies, dependingon the configuration. It will be appreciated that FIGS. 9A and 9B mayrepresent a cross-sectional views of treatment system 800 of FIGS. 8Aand 8B, for example. Light generated by UV-LEDs 950 is directed into afluid path defined as an interior space surrounded by the flexible UVlight generation sheet. When UV light reaches the UV diffuse reflectivelayer 920, the UV light is reflected back into the fluid path, allowingfor high levels of UV light intensity to be generated in the fluid path.In embodiments, reflective layer 920 is a highly diffuse reflectivematerial, such as a material that reflects 98% or more of incident UVlight, such as UV light having wavelengths between 100 nm and 400 nm, orany subrange thereof. As illustrated, each UV-LED 950 is positioned in aconfiguration that is not directly opposed to any other UV-LED 950.Stated another way, each UV-LED 950 is positioned in a configurationthat is directly opposed to reflective layer 920 to allow UV light toreflect off reflective layer 920 and become more uniformly distributed.It will be appreciated that, in the configuration illustrated in FIGS.9A-9B, the flexible UV light generation sheet may not include openingsin a UV diffuse reflective layer. Overlayer 960 is UV transparent andoptionally UV scattering (e.g., hazy) or comprises photocatalysts on thesurface. Overlayer 960 may optionally provide for protection ofunderlying or adjacent layers, and may, for example, provide protectionagainst penetration by water or another fluid.

FIG. 10 depicts a schematic cross-sectional illustration of a lightgeneration treatment system 1000. Such a configuration may beconstructed similar to the system 800 illustrated in FIGS. 8A and 8B,where a flexible UV light generation sheet is helically wrapped around atubular structure or where a flexible UV light generation sheet islongitudinally wrapped around a tubular structure. However, for lightgeneration treatment system 1000, the structure of the flexible UV lightgeneration sheet is reversed from the other embodiments. This enablesthe generation of an uniform UV emission field at a distance from theouter surface. For example, treatment system 1000 includes overlayer1060, UV-LEDs 1050, reflective underlayer 1030, and interior region1025. In FIG. 10, UV-LEDs 1050 are depicted as arranged to direct lightaway from a central shaft 1025 defined by the flexible UV lightgeneration sheet. Advantageously, overlayer 1060 may be a UVtransmissive scattering layer allowing light generated by UV-LEDs 1050to be scattered diffusely across a range of directions. Overlayer 1060may also serve as an encapsulating layer, providing water repellency andenvironmental protection to underlying UV-LEDs, conductors, and othercomponents.

Interior region 1025 may correspond to a tubular structure, such as ahollow tube or solid cylindrical structure, for example. An adhesive maybe used to mount the flexible UV light generation sheet to the interiorregion 1025. As an example, interior region may include a central shaft.Alternatively, the interior region may be open. In one example of aconstruction method an open interior region 1025 may be formed bywrapping a flexible UV light generation sheet around a mandrel. Hereinthe light generation sheet may be formed by first wrapping thereflective underlayer 1030 around the mandrel without an adhesive. Asecond underlayer 1030 may then be wrapped around the first underlayer1030 which includes a thin adhesive layer so as to secure the formfactor of the two underlayers 1030 in the shape of the mandrel butallowing the mandrel to be removed thereby forming an open interiorregion 1025.

Such a configuration is useful, for example, in embodiments where theflexible UV light generation treatment system 1000 is inserted into acontainer or fluid pathway and used to expose fluid, particles, orobjects in the container or fluid pathway to UV light. Treatment system1000 may correspond to a rod or stick that may be moved within thecontainer or fluid pathway to target impurities in the stream. Themovement may also induce turbulence and/or promote mixing.

FIG. 11 corresponds to two flexible UV light generation sheets opposingeach other and depicts a schematic cross-sectional illustration of aflexible UV light generation sheet useful for generating an uniform UVemission field at a distance from the flexible UV light generationsheet. As illustrated, the flexible UV light generation sheet 1100includes an underlayer 1120, UV-LEDs 1150 supported by the substrate andan overlayer 1160 positioned over underlayer 1120 and UV-LEDs 1150.Underlayer 1120 may correspond, for example, to a UV diffuse reflectivelayer. It will be appreciated that additional layers may be included inflexible UV light generation sheet 1100. For example multiple flexibleUV light generation sheets may be used together to form a system.Flexible UV light generation sheet 1100 may be useful, for example, forlining walls of a container or vessel to allow fluids, particles, orobjects within the container or vessel to be exposed to UV light fordisinfection, purification, or other treatment purposes. Optionally,devices within a container or vessel, such as used for mixing a fluid orobjects or particles suspended in a fluid, may have one or more surfaceslined with flexible UV light generation sheet 1100 to allow exposure ofthe fluid, objects, or particles to UV light for disinfection orpurification purposes. As an example, one or more walls of a vessel,conduit, or pipe may be lined with flexible UV light generation sheet1100 and/or a surface of a mixing vane may be lined with flexible UVlight generation sheet 1100.

As another example, one or more flexible UV light generation sheets maybe arranged in a pouch or pocket configuration, where a surface of afirst flexible UV light generation sheet faces a surface of a secondflexible UV light generation sheet. Such a configuration may correspondto two separate flexible UV light generation sheets or may correspond toa single flexible UV light generation sheet folded back on itself toform a pouch or pocket like configuration. As an example, for arectangular pouch configuration, three sides of facing rectangularflexible UV light generation sheets may be joined or attached to make arectangular pouch. Other shapes are possible.

As another example, multiple flexible UV light generation sheets may becombined to form a UV light generation system 1200, as depicted FIG. 12.In FIG. 12, UV light generation system 1200 includes a first flexible UVlight generation sheet 1205 and a second flexible UV light generationsheet 1210. First flexible UV light generation 1205 sheet may correspondto flexible UV light generation sheet 900 as depicted in FIG. 9. Secondflexible UV light generation sheet 1210 may correspond to flexible UVlight generation sheet 1000 as depicted in FIG. 10. As illustrated,first flexible UV light generation sheet 1205 and second flexible UVlight generation sheet 1210 are arranged so that second flexible UVlight generation sheet 1210 is positioned inside first flexible UV lightgeneration sheet 1210. In addition, the UV-LEDs of each flexible UVlight generation sheet are depicted as not directly opposed one anotherUV-LEDs. For example, UV light from UV-LEDS of first flexible UV lightgeneration sheet 1205 is directed towards a scattering layer or areflective layer of second flexible UV light generation sheet 1210.Similarly, UV light from UV-LEDS of second flexible UV light generationsheet 1210 is directed towards a reflective layer of first flexible UVlight generation sheet 1205. In this way, an annular region 1215 may beformed between first flexible UV light generation sheet 1205 and secondflexible UV light generation sheet 1210, such as to allow fluid to flowbetween them and be treated by UV light.

As another example, a flexible UV light generation sheet may optionallybe a two-sided sheet. Flexible two-sided flexible UV light generationsheet 1300 is depicted in FIGS. 13A and 13B. FIG. 13A shows across-sectional schematic illustration of two-sided flexible UV lightgeneration sheet 1300 including reflective layer 1320 and scatteringoverlayer 1360 covering reflective layer 1320 and UV-LEDs 1350. Asillustrated, UV-LEDs 1350 are mounted on both sides of two-sidedflexible UV light generation sheet 1300 with the reflective layer 1320and scattering overlayer positioned on each side of two-sided flexibleUV light generation sheet 1300. In this embodiment, UV-LEDs 1350positioned on a first side of the two-sided flexible sheet 1300 do notback to any UV-LEDs positioned on a second side of the two-sidedflexible sheet 1300. Flexible UV light generation sheet 1300 may becorrespond to a flag type configuration, where flexible UV lightgeneration sheet 1300 is fixed on one end with the other end free tomove, such as in a fluid. FIG. 13B also shows a supporting structure1370 and that flexible UV light generation sheet 1300 is supported only,for example, on one end by supporting structure 1370. In someembodiments, however, a flexible UV light generation sheet may besupported on two or more or all ends by various supporting structures.Supporting structure 1370 may include power and communicationsconnections, such as power/voltage supplies, control circuitry, orcommunications feeds, for example between UV-LEDs and/or UVphotodetectors and external circuitry by way of one or more conductors.It will be appreciated that FIG. 13B depicts a regular array of multipleUV-LEDs 1350 and that any conductors included with the array are notillustrated.

UV Diffuse Reflective Layer

A variety of materials are useful as a UV diffuse reflective layer forvarious flexible UV light generation sheets and treatment systemsdescribed herein. For example, a UV diffuse reflective layer maycomprise one or more polymers or a polymer layer, such as a polymerselected from the group consisting of a fluoropolymer, a polyimide, apolyolefin, a polyester, a polyurethane, a polyvinyl, polymethylmethacrylate, or variations or derivatives thereof. Example polymersinclude, but are not limited to, polyethylene terephthalate (PET),polyethylene naphthalate (PEN), poly ether ether ketone (PEEK), cyclicolefin copolymer (COC), polycarbonate (PC), polyphenylene sulfide (PPS),polyetherimide (PEI), polyamideimide (PAI), polychloroprene, polyvinylchloride (PVC), polyvinylidene chloride (PVDC), vinylidenechloride-vinyl chloride copolymers, vinyl chloride copolymers,vinylidene fluoride polymers, polyvinylidene fluoride (PVDF),fluorinated ethylene propylene (FEP), perfluoroalkoxy alkane (PFA), orpolytetrafluoroethylene (PTFE). In one embodiment, the UV diffusereflective layer may comprise an expanded polytetrafluoroethylene(ePTFE). In some embodiments, a UV reflective layer comprises a thinmetal film. In some embodiments, a UV reflective layer comprises adielectric stack. In some embodiments, a UV diffuse reflective layerexhibits a diffuse reflectivity of 50% or greater, 60% or greater, 70%or greater, 80% or greater, 90% or greater, 95% or greater, 97% orgreater, 98% or greater, or 99% or greater for UV light, such as lighthaving wavelengths between 200 nm and 400 nm. Example UV diffusereflective layers include those exhibiting a diffuse reflectivity(diffuse reflective scattering) percentage for UV light, such as lighthaving wavelengths between 200 nm and 400 nm, 50% or more (i.e.,50-100%), 60% or more, 70% or more, 80% or more, or 90% or more. In someembodiments, a UV diffuse reflective layer functions as anencapsulating, water resistance, or environmental protection layer.

A variety of exemplary materials that may be used as either a reflectivelayer, such as a reflective layer or a reflective underlayer. Inpublication “Reflectivity Spectra for Commonly Used Reflectors” byMartin Janacek, incorporated herein by reference, the author listsseveral materials which have greater than 97% reflectivity. In oneembodiment the UV diffuse reflective layer comprises ePTFE. The ePTFEmaterial comprises a microstructure of polymeric nodes and fibrils thatdemonstrates exceptional diffuse reflectivity in the UV spectrum. Anexemplary ePTFE for the UV diffuse reflective layer, Gore DRP®, isproduced by W.L. Gore & Associates of Newark, Del. FIG. 18 shows a plotof total reflectivity from 250 nm to 800 nm of various thicknesses ofskived PTFE along with Gore DRP®. This material is described in U.S.Pat. Nos. 5,596,450 or 6,015,610, the entire contents and disclosures ofwhich is hereby incorporated by reference. While packed granular basedPTFE material provides good diffuse reflectance properties, the node andfibril structure of ePTFE provides a much higher diffuse reflectanceproperty and has higher mechanical strength.

The UV diffuse reflective layer may be thin and lightweight. Making theUV diffuse reflective layer lighter and less expensive to employ expandsthe applications for the flexible UV light generation sheet. In oneembodiment the UV diffuse reflective layer, including any coating orfiller, may have a thickness from 0.01 mm to 2 mm, e.g., from 0.05 to1.5 mm or from 0.1 to 1.2 mm. In one embodiment, the UV diffusereflective layer has a high index of light reflection at a thickness ofless than 0.3 mm.

UV Transparent and Scattering Layers

A variety of materials are useful as a UV transparent layers or UVtransmissive scattering layer for various flexible UV light generationsheets and systems described herein. As noted above, UV transparentlayers and scattering layers are useful, for example, as overlayers.

In embodiments, a UV transparent layer or UV transmissive scatteringlayer may comprise one or more polymers or a polymer layer, such as apolymer selected from the group consisting of a fluoropolymer, apolyimide, a polyolefin, a polyester, a polyurethane, a polyvinyl,polymethyl methacrylate, or variations or derivatives thereof. Examplepolymers include, but are not limited to, polyethylene terephthalate(PET), polyethylene naphthalate (PEN), poly ether ether ketone (PEEK),cyclic olefin copolymer (COC), polycarbonate (PC), polyphenylene sulfide(PPS), polyetherimide (PEI), polyamideimide (PAI), polychloroprene,polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), vinylidenechloride-vinyl chloride copolymers, vinyl chloride copolymers,vinylidene fluoride polymers, polyvinylidene fluoride (PVDF),fluorinated ethylene propylene (FEP), perfluoroalkoxy alkane (PFA) orpolytetrafluoroethylene (PTFE). In some embodiments, a polymer useful asa UV transparent layer corresponds to a PTFE, such as an ePTFE, which isa highly inert hydrophobic material. Accordingly, the PTFE is chemicallyresistant and liquid-proof which is useful when the UV transparent layeror UV transmissive scattering layer is in contact with the fluid stream.In some embodiments, a UV transparent layer or UV transmissivescattering layer functions as an encapsulating, water resistance, orenvironmental protection layer.

Preferably, a UV transparent layer has a very low optical absorption(e.g., less than 10%, less than 5%, or less than 1%) so that a very highpercentage of the light is transmitted through the UV transparent layer.In some embodiments, a UV transparent layer exhibits a transparency forUV light of 50% or greater, 75% or greater, or 90% or greater, such aslight having wavelengths between 100 nm and 400 nm. In one embodiment,the UV transparent overlayer has a UV transmission of at least 80% at250 nm.

In addition to low optical absorption, an optional but desirableproperty for an overlayer is haze or scattering character. Haze isforward scattering of light greater than 2.5 degrees from the opticaltransmission axis. This property will defocus the light therebyincreasing the uniformity of the photon density in the fluid stream. Inembodiments, UV transmissive scattering layers comprise UV transparentmaterials. Inclusion of surface features or one or more fibrils, nodes,pores, and the like in a transparent material provides moreopportunities for scattering of light at surfaces or transitions betweenmaterials of different indices of refraction (e.g., air and polymer),and may provide a scattering character or haze to a material. Haze andscattering are further described in ASTM standard D1003, herebyincorporated by reference.

Exemplary overlayer materials are described in U.S. Pat. Nos. 5,374,473and 7,521,010, the entire contents and disclosures of which is herebyincorporated by reference. The patents describe a compressed ePTFEarticle which has improved properties over conventional cast or skivedPTFE. FIG. 19 shows a plot of transmission vs. wavelength for threesamples (S1, S2, S3) of a compressed ePTFE article as described in thepatents, along with FEP, PFA and ETFE (Tefzel™). The compressed ePTFEarticles have a thickness of 0.5 mil, while the FEP, PFA and ETFE have athickness of 1 mil. In general, thinner thicknesses will have highertransmission percentages due to lower absorption losses. However,T=1−R−A (Transmission calculates as 100% minus reflection losses R minusabsorption losses A) and in these films the reflection coefficient ismuch larger than the absorption coefficient (as calculated from thisequation using optical transmission and reflection data on the samefilms). So even higher transmission numbers can be attained by not usingair in the transmission path from the LED to the fluid medium. FIG. 20shows a plot of haze vs. wavelength for the same six articles. It willbe appreciated that in these samples the higher percent transmissionmaterial has the lower haze. Depending on the application, one maychoose to use a material with more scattering to promote light diffusionand reduce dark spots in the fluid stream even though the total opticalpower has been reduced. The overlayer material may have an opticaltransmission coefficient (T) of greater than 70% and a haze coefficient(H) of greater than 20% or preferably T>80% and H>50%.

An overlayer may be adhered or laminated to a UV diffuse reflectivelayer, a flex circuit, a substrate or supporting layer, the UV-LEDs, orany other material or layer in a flexible UV light generation sheet. Inone embodiment, an overlayer covers openings in a UV diffuse reflectivelayer that expose corresponding UV-LEDs.

Example UV transparent layers and UV transmissive scattering layers mayhave thicknesses of 7 microns to 100 microns.

UV transparent tube. In one embodiment, the assembly comprises a UVtransparent tube and the flexible UV light generation sheet is wrappedaround the tube. In one embodiment the flexible UV light generationsheet is wrapped along the outer surface of the tube. In otherembodiments, the flexible UV light generation sheet is wrapped and isplaced along the inner surface. The flexible UV light generation sheetis flexible and lack a structural rigidity to maintain the fluidpathway. A tube provides the necessary rigidity for the fluid pathway.This may be advantageous for in-line use for disinfection, purification,sterilization, or other treatment systems. The tube should be sufficientto withstand the temperature of the stream being treated and chemicallyresistant as needed.

In one embodiment, the UV transparent tube comprises a polymer, such asa fluoropolymer, a polyimide, a polyolefin, a polyester, a polyurethane,a polyvinyl, polymethyl methacrylate, polyethylene terephthalate (PET),polyethylene naphthalate (PEN), poly ether ether ketone (PEEK), cyclicolefin copolymer (COC), polycarbonate (PC), polyphenylene sulfide (PPS),polyetherimide (PEI), polyamideimide (PAI), polychloroprene, polyvinylchloride (PVC), polyvinylidene chloride (PVDC), vinylidenechloride-vinyl chloride copolymers, vinyl chloride copolymers,vinylidene fluoride polymers, polyvinylidene fluoride (PVDF),fluorinated ethylene propylene (FEP), perfluoroalkoxy alkane (PFA) orpolytetrafluoroethylene (PTFE). The material may be selected to providea rigidity to the flexible UV light generation sheet. However, in otherembodiments, the UV transparent tube may also be flexible.

Composite Structures

It will be appreciated that the various layers and components describedabove may be joined, adhered, or otherwise configured in a variety ofmanners to form a composite structure. For example, any one or more of asupport layer, a substrate, a conductor, a UV-LED, a UV diffusereflective layer, a UV transparent layer, a UV transmissive scatteringlayer, an encapsulating layer, and other components may be attached orpositioned adjacent to one another using any suitable means. In someembodiments, layers may be laminated to one another to allow for layersto be joined or attached in a composite structure. Example laminationprocesses include thermal-based lamination processes and adhesive-basedlamination processes. In some embodiments, layers or components may beattached or adjoined using one or more adhesives. Optionally, acontinuous adhesive layer is positioned between two objects to allow thetwo objects to be adjoined, such as where an adhesive layer ispositioned completely between the two objects at all points where thetwo objects are adjacent to one another. Optionally, a discontinuousadhesive layer, i.e. adhesive dots or adhesive lines, is positionedbetween two objects to allow the two objects to be adjoined, such aswhere a one or more adhesive layers are positioned between the twoobjects at only a subset of points where the two objects are adjacent toone another. Example adhesives include, but are not limited to,acrylics, polyamides, polyacrylamides, polyesters, polyolefins,polyurethanes, polysilicones or the like. Useful adhesives include thosethat do not impact the flexibility of the joined materials.

In embodiments, advantageous adhesives include UV stable adhesives. Asused herein, the term “UV stable” indicates that a material, such as anadhesive, is resistant to UV light, allowing long term use withoutdegrading. In some embodiments, a UV stable material may notsignificantly degrade when exposed to long durations of UV light, suchas years or more. Suitable UV stable adhesives include silicones,acrylates or adhesives with UV absorbers or inhibitors added thereto. Inaddition, UV stable material may advantageously be non-absorbing (i.e.,transparent) in the UV region or may exhibit only small amounts ofabsorption. Example UV stable materials include PTFE, ePTFE, fluorinatedethylene propylene (FEP) or perfluoroalkoxy alkane (PFA). Example UVstable adhesives include thermoplastic fluoropolymers. Preferredadhesives are FEP, a copolymer of tetrafluoroethylene andhexafluoropropylene; PFA, a copolymer of tetrafluoroethylene monomerscontaining perfluoroalkoxy side chains, and EFEP, a copolymer ofethylene, tetrafluoroethylene, and hexafluoropropylene. Alternatively,copolymer resins of tetrafluoroethylene and perfluoroethylene-alkylether monomers (e.g., PAVE, PMVE, and/or CNVE) can be made withcompositions and molecular weights to act as adhesives that exhibitexcellent thermal and UV resistance (pressure sensitive, thermoplastic,or crosslinked). Such copolymer resins are disclosed, for example, inU.S. Pat. Nos. 7,488,781; 8,063,150; 8,623,963; 7,462,675; and7,049,380.

UV-LED Configurations

UV-LEDs may be incorporated in the flexible UV light generation sheetsand treatment systems described herein in a variety of manners. Todistribute the UV light within the fluid pathway the UV-LEDs arearranged to form a regular spacing about the flexible UV lightgeneration sheet. In other embodiment, non-regular spacing of theUV-LEDs may also be used. Multiple UV-LEDs are arranged in a parallel orseries configuration. For example, FIG. 14 provides an example circuitdiagram 1400 showing multiple UV-LEDs 1450. As illustrated, an LED powersupply 1405 is shown driving three sets of three series connectedUV-LEDs 1450, such that each UV-LED 1450 in a series is driven by thesame amount of current. FIG. 15 provides another example circuit diagram1500 showing multiple UV-LEDs 1550. As illustrated, LED power supply1505 drives the UV-LEDs 1550 in parallel, such that each UV-LED 1550 isdriven by the same voltage, for example. It will be appreciated that theconfiguration illustrated in FIG. 14 depicts not only UV-LEDs connectedin series, but also series connected UV-LEDs that are also connected ina parallel configuration.

In some embodiments, UV-LEDs incorporated into flexible UV lightgeneration sheets and treatment systems correspond to surface mountingdevices, which may be advantageous for some implementations. Forexample, in some embodiment where flat flexible cable-based conductorsare used, surface mounting of UV-LEDs may have dimensions that match thepitch between conductors, allowing for seamless integration andmanufacture of a flexible UV light generation sheet.

In some embodiments, UV-LEDs useful with the flexible UV lightgeneration sheets and treatment systems described herein include UVALEDs, exhibiting emission between wavelengths of 315 nm and 400 nm. Insome embodiments, UV-LEDs useful with the flexible UV light generationsheets and treatment systems described herein include UVB LEDs,exhibiting emission between wavelengths of 280 nm and 315 nm. In someembodiments, UV-LEDs useful with the flexible UV light generation sheetsand treatment systems described herein include UVC LEDs, exhibitingemission between wavelengths of 100 nm and 280 nm. Exemplary UV-LEDsemit UV light with wavelengths between 260 nm and 265 nm, between 270 nmand 280 nm, 305 and 315 nm. It will be appreciated, however, that thewavelength of UV light and the associated UV-LEDs may be selected thatbest matches or at least partially overlaps a destruction effectivenesscurve of a target toxin or target pathogen, for example. As an example,a germicidal effectiveness curve for Escherichia coli may exhibit a peakat about 265 nm, and use of UV-LEDs emitting at this wavelength mayprovide an advantage for destroying these pathogens or toxins in thefluid pathway.

A variety of UV-LED structure types are suitable for use with theflexible UV light generation sheets and treatment systems describedherein. In some embodiments, a UV-LED, one or more UV-LEDs or eachUV-LED corresponds to a surface-mount device. Use of surface-mountdevices are advantageous when making a flexible UV light generationsheet or a treatment system using a flat flexible cable, as certain flatflexible cables have standard pitches between conductors or widths thatmay match commercially available surface-mount type UV-LEDs. Otheradvantages provided by the use of surface-mount structures include theability to use pick-and-place machinery to assemble portions of aflexible UV light generation sheet or treatment system. Other types ofUV-LED structures are useful for some embodiments described herein,including through-hole LEDs, miniature LEDs, high-power LEDs, round,square, etc. In addition, any LED structure capable of generating UVlight of a desired wavelength or wavelength region are useful with theembodiments described herein. For example, in some embodiments, a UV-LEDhas an AlGaN-structure, AlN structure, a GaN structure, or combinationsof these.

It is to be understood that other UV light emitting semiconductors, suchas laser diodes, for example VCSELs (vertical cavity surface emittinglasers), are considered UV-LEDs for the purposes of this patentapplication

Feedback and Intensity Control

It will be appreciated that exposure of toxins or pathogens to aparticular dose of UV light may result in destruction of the toxins orpathogens, while lower doses may not completely destroy the toxins orpathogens. Similarly, if the toxin or pathogen is present in higherconcentrations, the particular dose may not sufficiently destroy thetoxins or pathogens. Advantageously, flexible UV light generation sheetsand treatment systems described herein optionally include feedbackmechanisms that permit control over the dose or output intensity of UVlight generated. As an example, in some embodiments, a flexible UV lightgeneration sheet or treatment system may include one or more UV sensors.For example, in the configurations illustrated in FIGS. 1-13B, one ormore UV-LEDs may be substituted for a UV sensitive photodetector, suchas a photodiode, that is positioned in electrical communication with amonitoring circuit that is used to provide feedback for increasing ordecreasing a current and/or voltage used to drive one or more UV-LEDs inorder to maintain a suitable UV light field.

FIG. 16 provides an example circuit diagram 1600 in which multipleUV-LEDs 1650 are driven by LED power supply 1605. A UV sensitivephotodetector 1670 is depicted as connected to a power monitor circuit1680 that may be used to monitor a UV light intensity or power as outputby the UV-LEDs 1650. By monitoring a UV light intensity or power, thepower monitor circuit 1680 may provide information, used, such as by thepower monitor circuit or another computer or control circuitry, toadjust the voltage or current generated by LED power supply 1605. Inthis way, the intensity of UV light can be monitored and adjusted toaccommodate a target UV light dose or intensity useful for destroyingtoxins or pathogens.

Methods of Making Treatment Systems

It will be appreciated that a variety of techniques may be employed formaking the treatment systems and flexible UV light generation sheetsdescribed herein. FIGS. 17A-17F provide schematic overviews of anexample aspects of an embodiment of a method of making a flexible UVlight generation sheet. FIGS. 17A-17F provide schematic cross-sectionalfront views (1), side views (2), and top views (3) of a flexible UVlight generation sheet during steps of a fabrication method. In FIG.17A, multiple conductors 1702 are illustrated, each corresponding to aflat conductor of a flat flexible cable 1704. For purposes ofillustration, only a section of a conductor cable is shown, but it willbe appreciated that conductors of any number and size may be useful withvarious embodiments of the invention. Optionally, the jacketingsurrounding the conductors may be UV transmissive or reflectivepolymers. In FIG. 17B, the flat flexible cable 1704 is positionedadjacent to a substrate 1706. In FIG. 17C, a UV diffuse reflective layer1708 is positioned adjacent to the flat flexible cable 1704. In FIG.17D, openings 1710 are created at locations over two of the flatconductors 1702, through both the UV diffuse reflective layer 1708 andthe jacketing of the flat flexible cable 1704. In addition, in FIG. 17D,two of the flat conductors 1702 are segmented. Openings may be createdusing known processes in the industry, such as laser ablating ormechanical cutting. In FIG. 17E, UV-LEDs 1712 are positioned in eachopening and joined to the respective flat conductor segments 1702.UV-LEDs may be attached using known processes in the industry, such assoldering or epoxying. In FIG. 17F, an overlayer 1714 is providedadjacent to the UV diffuse reflective layer, such as a UV transmissivescattering layer or a UV transparent layer. The attachment of thesubstrate, reflective, or transparent layers may be facilitated with theuse of adhesives.

It will be appreciated that, for some embodiments, a separate substratemay not be required. For example a jacketing of a conductor may providea suitable support structure for the conductors. Alternatively oradditionally, an overlayer may not be required for some embodiments. Itwill further be appreciated that some embodiments may not require a UVdiffuse reflective layer and so the UV diffuse reflective layer may besubstituted for a UV transparent layer or a UV transmissive scatteringlayer.

The so formed flexible UV light generation sheets may be arranged in aconfiguration for exposing a fluid to UV light generated by the flexibleUV light generation sheet. For example, the flexible UV light generationsheet may be arranged to enclose a fluid pathway. As another example,the flexible UV light generation sheet may be arranged to form a tubularshape. Optionally, the flexible UV light generation sheet may behelically wrapped, longitudinally wrapped, or circumferentially wrappedaround a tube or central shaft. Optionally, the flexible UV lightgeneration sheet may be arranged along an interior surface of a vesselor along a surface of a structure positioned within a vessel.

An overview of a method 2100 for the assembly of a UV light generatingsheet, such as depicted in FIG. 7A, is shown in FIG. 21. At block 2105,multiple UV-LEDs are attached to the flexible circuit via knownpractices in the industry, such as surface mounting technology, whichincludes chip on board and SMD attachment. The UV-LEDs may be insemiconductor die form and flip-chipped or wirebonded to the flexcircuit conductive traces in a chip on board process. Alternatively, theUV-LEDs may be already packaged in a SMD (surface mount device) carrierpackage, where the UV-LED packages are attached to the flexible circuitwith conductive adhesives or solders. In some embodiments, the flexiblecircuit is made by a method that includes removing portions of ajacketing of the ribbon cable or flat flexible cable to expose UV-LEDsor attachment locations for the UV-LEDs. It will be appreciated that theflexible circuit may be substituted by a ribbon cable or other flexibleconductor assembly, as described above. The UV LEDs have a predeterminedspacing that is used to create the openings in block 2115. At block2110, an adhesive layer is applied to a surface of the UV diffusereflective sheet. As described herein the adhesive layer for each layeror sheet may be a continuous layer of film or a pattern of dots orlines. Preferable adhesives are thermoplastic fluoropolymers such as FEP(melting point (mp) 260° C.), PFA (mp 305° C.), THV (mp 120-230° C.),and EFEP (mp 158-196° C.). In other embodiments, an adhesive layer mayalternatively or additionally be applied to the top of the flexiblecircuit. Openings are cut into the UV diffuse reflective sheet at block2115. Next, the UV diffuse reflective sheet is positioned to alignopenings with the UV-LEDs, at block 2120. By a similar method, anadhesive layer is applied to one surface of a transparent overlayersheet, as depicted at block 2125. In block 2130, the transparentoverlayer sheet is positioned adjacent to a surface of the UV diffusereflective sheet opposite to the flexible circuit. At block 2145, theassembly is cured in an oven or preferably in a heated press at atemperature from 125 to 325° C. In one optional embodiment, theunderlayer sheet can be added by a similar method at blocks 2135 and2140. Although optional block 2135 indicates that the adhesive layer maybe attached to the underlayer sheet, the adhesive layer mayalternatively or additionally be applied to the bottom of the flexiblecircuit.

The assembly of the double-sided UV light generating sheet, such as theflag configurations shown in FIGS. 13A and 13B, is similar to method2100 as depicted in FIG. 21. In this case the UV-LEDs are mounted on twosides of the flexible circuit and there is no optional reflectiveunderlayer sheet. In this design, the UV-LEDs are not back-to-back so,for practical purposes, the UV diffuse reflective sheet next to the topUV-LEDs functions as the UV diffuse reflective sheet underlying theUV-LEDs on the opposite side. Alternatively, a single-sided UV lightgenerating sheet may be folded back on to itself to create the flagconfigurations in FIGS. 13A and 13B.

A method for making a light generating tube, such as depicted in FIGS.8A and 8B, involves wrapping a light generating sheet around a mandrel,such as a mandrel of the desired tubular shape. The wrapping may behelical, longitudinal, or circumferential to form the desired tubularshape. The mandrel is a cylindrical rod made of a material, such as ametal, that can withstand the cure temperatures used in the method. Thewrapped sheet is then further wrapped with an underlayer, such as areinforcing layer, optionally with an adhesive, and cured to solidifythe assembly. Further protective coatings may be applied over the tubeassembly. Cure steps may optionally be done at different points in themethod. The mandrel is then removed from the tube assembly to create thefluid path.

A method 2200 is shown in FIG. 22 for wrapping a light generating sheetin tubular form. A flexible circuit comprising multiple UV-LEDs isassembled, in a manner described herein, at block 2205. An adhesive isapplied to one surface of a UV diffuse reflective layer at block 2210,and openings are cut in the UV diffuse reflective layer at block 2215.The flexible circuit is aligned with the UV diffuse reflective layer atblock 2220 such that the openings align with the UV-LEDs to form a UVlight generating sheet. The UV light generating sheet is then wrappedaround a mandrel at block 2225. An underlayer, which optionally may be areinforcing layer with reflective properties, is wrapped around the UVlight generating sheet with an adhesive, as shown at blocks 2230 and2235. Additional layers or coatings may optionally be added to theoutside of the tubular assembly. At block 2240, the assembly is thencured, for example in an oven, and the mandrel is removed, at block2245. In one embodiment, a lower melting point fluoropolymer adhesiveEFEP is used so the curing temperature does not harm the flexiblecircuit. The product embodiment of this method may correspond to, forexample, that shown in FIG. 9A.

Another method 2300 is shown in FIG. 23, which may form a productcorresponding to, for example, that shown in FIG. 9B. At block 2305, atransparent overlayer (e.g., layer 960 in FIG. 9B), is wrapped around amandrel to form a tube, optionally with an adhesive applied at block2310. The transparent overlayer can be made of materials describedpreviously. The transparent overlayer can optionally be multilayerwrapped several times with an adhesive to secure the transparentoverlayer to itself but not to the mandrel. In other embodiments, thetransparent overlayer is a tube that is slid over the mandrel. Thetransparent overlayer is optionally cured at this stage. In an exemplarymethod, a preferred transparent overlay material is the aforementionedcompressed ePTFE material, the adhesive is FEP, and the tubularstructure is cured at 280° C. (a temperature greater than the adhesivemelting temperature but less than the melting temperature of thetransparent overlay material). An alternative method of fabricating thetransparent overlayer (e.g., layer 960 in FIG. 9B), is to slide apre-manufactured FEP tube over the mandrel. In this example, thefollowing cure temperature steps should be less than the meltingtemperature of the FEP so as to enable the mandrel to be removed fromthe tubular assembly. After the transparent tube is formed, the rest ofthe method is similar to that described in FIG. 22. For example, aflexible circuit comprising multiple UV-LEDs is assembled at block 2315.An adhesive is applied to one surface of a UV diffuse reflective layerat block 2320, and openings are cut in the UV diffuse reflective layerat block 2325. The flexible circuit is aligned with the reflective layerat block 2330 such that the openings in the layer align with the UV-LEDsto form the UV light generating sheet. The UV light generating sheet isthen wrapped around the transparent overlayer at block 2335. Anadditional underlayer, which optionally may be a reinforcing layer or UVdiffuse reflective layer, is wrapped around the assembly using anadhesive layer, as shown at blocks 2340 and 2345. Additional layers orcoatings may optionally be added to the outside of the UV lightgenerating sheet. At block 2350, the assembly is then cured, for examplein an oven, and the mandrel is removed, at block 2355.

The methods shown by FIGS. 21-23 create openings in the UV diffusereflective sheet. In other embodiments, openings may be created by gapsbetween adjacent longitudinal sides as described by the methods in FIGS.24-26. Regardless of the method of making UV light generating system,once in use the process may comprise energizing the multiple UV-LEDs togenerate UV light, wherein at least a portion of the generated UV lightfrom the multiple UV-LEDs passes through the corresponding openings andinto the fluid pathway.

In one embodiment, reflective layers may be wrapped by the method thatis shown by FIGS. 24A-24E. A mandrel 2402, e.g., a cylindrical rod, isused to form a tubular UV light generation system 2400 and once formedthe mandrel 2402 is removed to form the fluid path. In one embodiment asshown in FIG. 24A, a transparent material 2404 is wrapped around themandrel 2402 to form an overlayer. The wrapping is done to prevent gapsbetween the adjacent longitudinal sides of the transparent material2404. Optionally, adjacent longitudinal sides of the transparentmaterial overlap. In other embodiments, a transparent overlayer that istubular may be fitted around the mandrel 2402, by sliding thetransparent overlayer over the mandrel 2402. The overlayer may have anadhesive surface of a continuous transparent adhesive or by a pattern ofadhesive dots or adhesive lines facing outward. Next, a UV diffusereflective layer 2406 is wrapped around the mandrel 2402, or overlayerif present. When being wrapped, a gap 2408 is formed between adjacent,e.g., nearby, longitudinal sides of the UV diffuse reflective layer2406. The UV diffuse reflective layer 2406 is wrapped along the lengthof the mandrel to the desired size. The UV diffuse reflective layer 2406may have an adhesive surface of a transparent adhesive or by a patternof adhesive dots or adhesive lines facing outward. In one embodiment,the UV diffuse reflective layer 2406 is flexible and may be made of a UVstable material, e.g., expanded polytetrafluoroethylene. The gap 2408may be substantially uniform between the adjacent sides to provide aseparation distance between the adjacent sides from 0.5 to 100 mm,preferably 0.5 to 20 mm, e.g., 1 to 25 mm, or from 3 to 15 mm. Aflexible circuit 2410 having multiple UV-light emitting diodes 2412 ispositioned to align the UV-light emitting diodes 2412 with the gap 2408.This allows the UV light to be transmitted into the interior of the UVlight generating system 2400 when in use. Although one flexible circuitis shown in FIG. 24C, in further embodiments, multiple flexible circuitsmay be used adjacent to the UV diffuse reflective layer 2406. Whenmultiple flexible circuits are used, UV-light emitting diodes areoff-set to achieve a wide distribution of UV light within the UV lightgenerating system 2400. In FIG. 24D, an underlayer 2414 is wrapped overthe UV diffuse reflective layer and flexible circuit. The wrapping isdone to prevent gaps between the adjacent longitudinal sides of theunderlayer 2414. Optionally, adjacent longitudinal sides of underlayer2414 overlap. One or more curing processes may optionally be included inthe method depicted in FIGS. 24A-24E, and following FIG. 24E, themandrel 2402 may be removed to create an internal fluid path.

Optionally, flexible circuit 2410 may itself include a diffuse UVreflective overlayer with openings included at the positions of UV LEDs2412, as described above. Such a flexible circuit may alternatively bewrapped in a helical fashion around the mandrel 2402, or overlayer 2404if present, with the gap 2408 having a width that is greater than orequal to the width of flexible circuit 2410 to allow flexible circuit2410 to fit into the helical gap 2408, as indicated in FIG. 24F. Thisconfiguration may be used in place of or in addition to that depicted inFIG. 24D. This configuration benefits from a longer flexible circuit2410 that may include more UV-LEDs and enables tighter curvatures withthe tube assembly in a bent configuration.

In a further embodiment, the method may involve wrapping a second UVdiffuse reflective layer 2516 as shown in FIGS. 25A-25F. As discussedabove, a first UV diffuse reflective layer 2506 is wrapped around themandrel 2502, and optionally, the transparent material 2504 that formsthe overlayer, such that a first gap 2508 is present between adjacent,e.g. nearby, longitudinal sides of first UV diffuse reflective layer2506. In FIG. 25C, the second UV diffuse reflective layer 2516 iswrapped around the first UV diffuse reflective layer 2506. In oneembodiment, the second UV diffuse reflective layer 2516 iscounter-wrapped in a direction that is opposite to the first UV diffusereflective layer 2506. In further embodiments, additional UV diffusereflective layers may be used. The second gap 2518 between adjacent,e.g., nearby, longitudinal sides of the second UV diffuse reflectivelayer 2516 overlap with the first gap 2508 to form openings 2520. Asdiscussed herein, the openings 2520 may have a variety of shapes andsizes. The openings 2520 correspond to the pitch of the spacing ofUV-LEDs 2512 on a flex circuit 2510. In one example, a 0.5 inch wide,0.01 inch thick, ePTFE layer was wrapped at a pitch of 17 mm with a gapof 4 mm in the right hand direction and then a second ePTFE layer wascrossed wrapped in the left hand direction at a pitch of 17 mm with agap of 4 mm. The resulting opening in the reflective layers is 4 mmdiamond on a pitch of 17 mm. In one embodiment, the overlap of the firstgap and second gap may create several different openings. For example,there may be additional openings on the back side (not shown in FIG.25D) that are spaced halfway between the openings on the top side.

FIG. 25D shows the flex circuit 2510 having UV-LEDs 2512 laid straightin a longitudinal manner. In one embodiment, multiple flex circuits maybe used. In another embodiment, the method includes helically wrapping aflex circuit having UV-LED in a helical fashion around the tube, thespacing of the UV-LEDs being such that they align with the openings.This embodiment benefits from a longer flexible circuit that enablestighter curvatures with the tube assembly in a bent configuration. Asshown in FIG. 25F, optional underlayer 2514 is wrapped around theassembly, which may have reflective or diffuse reflective properties.

To complete the tubular UV light generation system 2500 assembly, theassembly is then cured and the mandrel 2502 is removed to create theinternal fluid path.

As previously described, an optional embodiment for the transparentoverlayer is to include photocatalysts such as TiO2 on the surface thatis exposed to the fluid medium. In previously described embodiments, theoverlayer is positioned above the UV-LED such that the emitted lightpath is from LED to photocatalyst to fluid medium. Since thephotocatalysts in touch with the fluid medium are generally moreeffective at generating reactive oxygen species that can disinfect thefluid stream, it may be desirable to have an optical path from LEDthrough fluid stream to surface photocatalysts (e.g., on other side oftube). FIGS. 26A and 26B depict an embodiment of forming the transparentoverlayer that will enable the light emitted from the UV-LED to impingeon the photocatalysts from the fluid medium side. A first transparentoverlayer 2603 is wrapped around mandrel 2602 with a gap 2605 as shownin FIG. 26A. A second overlayer 2607, comprising a photocatalyticsurface layer, optionally of the same width as gap 2605, is then wrappedin the gap of transparent overlayer 2603 as shown in FIG. 26B. At thisstage in the process the transparent overlayer equivalent to FIG. 24A orFIG. 25A is finished and the various steps described in FIG. 24B-24F or25B-25F can be implemented to finish construction of the photocatalyticlight generating tube. An optional embodiment is described in FIG. 24Fwith the addition of a photocatalytic layer to the UV reflective layer2406.

Additional Examples

Additional non-limiting examples are further described.

E1. A method of making an ultraviolet (UV) light generation system, themethod comprising: wrapping a first UV diffuse reflective layer in afirst direction around a mandrel with a first gap between adjacentlongitudinal sides of the first UV diffuse reflective layer, wherein thefirst UV diffuse reflective layer is flexible; and positioning aflexible circuit including multiple UV-light emitting diodes (UV-LEDs)adjacent to the first UV diffuse reflective layer, wherein thepositioning of the flexible circuit includes aligning the multipleUV-LEDs to correspond to the first gap.

E2. The method of E1, further comprising wrapping a second UV diffusereflective layer in a second direction around the mandrel and the firstUV diffuse reflective layer with a second gap between adjacentlongitudinal sides of the second UV diffuse reflective layer, whereinthe second UV diffuse reflective layer is flexible, and wherein aportion of the first gap and a portion of the second gap overlap togenerate a plurality of openings.

E3. The method of E2, wherein the positioning the flexible circuitincludes aligning the multiple UV-LEDs to correspond to the pluralityopenings.

E4. The method of E2, wherein each of the multiple UV-LEDs is positionedto direct generated UV light through a corresponding opening.

E5. The method of any one of E1-E4, wherein wrapping of the first UVdiffuse reflective layer includes helically wrapping.

E6. The method of any one of E1-E5, wherein each of the multiple UV-LEDsis positioned to direct generated UV light through the first gap.

E7. The method of any one of E1-E6, wherein aligning the multipleUV-LEDs includes aligning one or more UV-LEDs of a first flexiblecircuit at a first subset of the plurality of openings and aligning oneor more UV-LEDs of a second flexible circuit at a second subset of theplurality of openings.

E8. The method of E7, wherein the first subset of the plurality ofopenings and the second subset of the plurality of openings arepositioned on opposite sides of the mandrel.

E9. The method of E7, wherein the first subset of the plurality ofopenings and the second subset of the plurality of openings are offsetfrom one another.

E10. The method of any one of E1-E9, further comprising generating theflexible circuit.

E11. The method of E10, wherein generating the flexible circuit includesattaching the multiple UV-LEDs.

E12. The method of E11, wherein attaching the multiple UV-LEDs includessurface mounting the multiple UV-LEDs on the flexible circuit.

E13. The method of E10, wherein the flexible circuit comprises a ribboncable or flat flexible cable and wherein generating the flexible circuitincludes attaching the multiple UV-LEDs to the ribbon cable or flatflexible cable.

E14. The method of E13, wherein generating the flexible circuit furtherincludes removing portions of a jacketing of the ribbon cable or flatflexible cable.

E15. The method of any one of E1-E14, further comprising wrapping anunderlayer around the mandrel, the first UV diffuse reflective layer,and the flexible circuit.

E16. The method of E15, wherein the underlayer is a reinforcingunderlayer.

E17. The method of E15, wherein the underlayer is a UV diffusereflective underlayer.

E18. The method of E15, further comprising applying an adhesive betweenthe underlayer the flexible circuit and the first UV diffuse reflectivelayer.

E19. The method of any one of E1-E18, further comprising wrapping anoverlayer around the mandrel, wherein wrapping the first UV diffusereflective layer around the mandrel includes wrapping the first UVdiffuse reflective layer around the overlayer and the mandrel.

E20. The method of any one of E1-E18, further comprising positioning atubular overlayer around the mandrel, wherein wrapping includes wrappingthe first UV diffuse reflective layer around the tubular overlayer andthe mandrel.

E21. The method of any one of E19 or E20, wherein the overlayer ortubular overlayer is a UV transparent overlayer, preferably having a UVtransmission of at least 80% at 250 nm.

E22. The method of any one of E19 or E20, wherein the overlayer ortubular overlayer is a UV transmissive scattering overlayer.

E23. The method of any one E19 or E20, wherein the overlayer or tubularoverlayer comprises a photocatalyst, preferably comprises TiO2.

E24. The method of any one of E19 or E20, further comprising applying anadhesive between the first UV diffuse reflective layer and the overlayeror tubular overlayer, preferably wherein the adhesive is a fluorinatedethylene propylene (FEP) adhesive.

E25. The method of any one of E1-E24, further comprising energizing themultiple UV-LEDs to generate UV light, wherein at least a portion of thegenerated UV light from the multiple UV-LEDs passes through thecorresponding openings and into the fluid pathway.

E26. The method of any one of E1-E25, further comprising removing themandrel.

E27. An ultraviolet (UV) light generation system made by the method ofany one of E1-E26.

E28. An ultraviolet (UV) light generation system comprising: a first UVdiffuse reflective layer arranged about a fluid pathway, whereinadjacent longitudinal sides of the first UV diffuse reflective layer areseparated by a first gap, wherein the first gap runs in a firstdirection, and wherein the first UV diffuse reflective layer isflexible; a second UV diffuse reflective layer arranged about the firstUV diffuse reflective layer, wherein adjacent longitudinal sides of thesecond UV diffuse reflective layer are separated by a second gap,wherein the second gap runs in a second direction, wherein the second UVdiffuse reflective layer is flexible, and wherein the first and secondgap overlap to generate a plurality of openings; and a flexible circuitincluding multiple UV-light emitting diodes (UV-LEDs), wherein theflexible circuit is positioned adjacent to the second UV diffusereflective layer to align the multiple UV-LEDs at the plurality ofopenings.

E29. The UV light generation system of E28, wherein the first UV diffusereflective layer is cylindrically wrapped about the fluid pathway, orwherein the second UV diffuse reflective layer is cylindrically wrappedabout the first UV diffuse reflective layer, or both.

E30. The UV light generation system of E28 or E29, wherein the first UVdiffuse reflective layer is helically wrapped about the fluid pathway,or wherein the second UV diffuse reflective layer is helically wrappedabout the first UV diffuse reflective layer, or both.

E31. The UV light generation system of any one of E28-E30, furthercomprising an overlayer arranged about and defining the fluid pathway,wherein the first UV diffuse reflective layer is wrapped about theoverlayer.

E32. The UV light generation system of E31, wherein the overlayer is aUV transparent overlayer, preferably having a UV transmission of atleast 80% at 250 nm.

E33. The UV light generation system of E31, wherein the overlayer is aUV transmissive scattering overlayer.

E34. The UV light generation system of E31, wherein the overlayercomprises a photocatalyst, preferably comprises TiO2.

E35. The UV light generation system of E31, wherein the overlayer coversat least a portion of the plurality of openings.

E36. The UV light generation system of E31, wherein the overlayer is UVstable.

E37. The UV light generation system of E31, wherein the overlayer isadhered to the first UV diffuse reflective layer or laminated to thefirst UV diffuse reflective layer, preferably the overlayer comprises aphotocatalyst, and more preferably comprises TiO2.

E38. The UV light generation system of any one of E28-E37, wherein thefirst UV diffuse reflective layer does not include UV absorbing fillermaterial, or wherein the second UV diffuse reflective layer does notinclude UV absorbing filler material, or both.

E39. The UV light generation system of any one of E28-E38, wherein thefirst UV diffuse reflective layer is UV stable, or wherein the second UVdiffuse reflective layer is UV stable or both.

E40. The UV light generation system of any one of E28-E39, furthercomprising an underlayer wrapped around the flexible circuit, the firstUV diffuse reflective layer, and the second UV diffuse reflective layer.

E41. The UV light generation system of E40, wherein the underlayer is areinforcing underlayer.

E42. The UV light generation system of E40, wherein the underlayer is aUV diffuse reflective underlayer.

E43. The UV light generation system of any one of E28-E42, wherein themultiple UV-LEDs are positioned to direct generated UV light into thefluid pathway.

E44. The UV light generation system of any one of E28-E43, wherein atleast a first UV-LED of the multiple UV-LEDs is positioned in aconfiguration about the fluid pathway that is not directly opposed toany other of the multiple UV-LEDs.

E45. The UV light generation system of any one of E28-E44, wherein thefluid pathway corresponds to a tubular shape.

E46. The UV light generation system of any one of E28-E45, wherein thefluid pathway corresponds to a liquid pathway and wherein exposing aliquid stream in the liquid pathway to UV light generated by themultiple UV-LEDs reduces impurities within the liquid stream or reducesimpurities associated with particles suspended in the liquid stream.

E47. The UV light generation system of any one of E28-E46, wherein thefluid pathway corresponds to a gas pathway and wherein exposing a gasstream in the gas pathway to UV light generated by the multiple UV-LEDsreduces impurities within the gas stream or reduces impuritiesassociated with particles suspended in the gas stream.

E48. The UV light generation system of any one of E28-E47, wherein theflexible circuit further includes a UV sensitive photodetector, whereinthe UV sensitive photodetector is positioned at one of the plurality ofopenings.

E49. The UV light generation system of any one of E28-E48, furthercomprising an adhesive layer for adhering two or more components of theUV light generation system to one another.

E50. The UV light generation system of E49, wherein the adhesive layeradheres a layer, an overlayer, or an underlayer to other components ofthe UV light generation system.

E51. The UV light generation system of E49, wherein the adhesive layercorresponds to a UV transparent layer, preferably wherein the adhesiveis a fluorinated ethylene propylene (FEP) adhesive.

E52. The UV light generation system of E49, wherein the adhesive layeris UV stable.

E53. The UV light generation system of any one of E28-E52, wherein theflexible circuit corresponds to a ribbon cable or a flat flexible cable.

E54. The UV light generation system of any one of E28-E53, wherein eachof the multiple UV-LEDs are individually electrically addressable.

E55. The UV light generation system of any one of E28-E54, wherein atleast a portion of UV light generated by the multiple UV-LEDs isreflected by a UV diffuse reflective layer of the UV light generationsystem.

E56. The UV light generation system of any one of E28-E55, wherein themultiple UV-LEDs are positioned about the UV light generation system ina configuration to generate a uniform UV emission field within the fluidpathway.

E57. The UV light generation system of any one of E28-E56, wherein thefluid pathway includes straight or curved sections.

E58. The UV light generation system of any one of E28-E57, wherein oneor more layers, underlayers, or overlayers of the UV light generationsystem are flexible or exhibit an elastic modulus of between 0.001 GPaand 3.0 GPa.

E59. The UV light generation system of any one of E28-E58, wherein oneor more layers, underlayers, or overlayers of the UV light generationsystem comprise polytetrafluoroethylene orexpanded-polytetrafluoroethylene (e-PTFE).

E60. The UV light generation system of any one of E28-E59 made by themethod of any one of E1-E27.

E61. The method of any one of E1-E27, wherein the UV light generationsystem comprises the UV light generation system of any one of E28-E59.

E62. A method of making an ultraviolet (UV) light generation system, themethod comprising: generating a plurality of openings in a UV diffusereflective layer, wherein the UV diffuse reflective layer is flexible;and positioning a flexible circuit adjacent to the UV diffuse reflectivelayer, wherein the flexible circuit includes multiple UV-light emittingdiodes (UV-LEDs), and wherein the multiple UV-LEDs are aligned atcorresponding openings in the UV diffuse reflective layer.

E63. The method of E62, wherein generating the plurality of openingsincludes removing portions the UV diffuse reflective layer.

E64. The method of E62 or E63, further comprising generating theflexible circuit.

E65. The method of E64, wherein generating the flexible circuit includesattaching the multiple UV-LEDs on a flexible circuit.

E66. The method of E65, wherein attaching the multiple UV-LEDs includessurface mounting the multiple UV-LEDs on the flexible circuit.

E67. The method of E64, wherein the flexible circuit comprises a ribboncable or flat flexible cable and wherein generating the flexible circuitincludes attaching the multiple UV-LEDs to the ribbon cable or flatflexible cable.

E68. The method of E64, wherein generating the flexible circuit furtherincludes removing portions of a jacketing of the ribbon cable or flatflexible cable.

E69. The method of any one of E62-E68, wherein the flexible circuit is atwo-sided flexible circuit, wherein generating the plurality of openingsin the UV diffuse reflective layer includes generating a first pluralityof openings in a first UV diffuse reflective layer and generating asecond plurality of openings in a second UV diffuse reflective layer UV,and wherein positioning the flexible circuit includes aligning a firstportion of the multiple UV-LEDs that are present on a second side of thetwo-sided flexible circuit with corresponding openings of the first UVdiffuse reflective layer and aligning a second portion of the multipleUV-LEDs that are present on a second side of the two-sided flexiblecircuit with corresponding openings of the second UV diffuse reflectivelayer, thereby making a two-sided UV light generation system.

E70. The method of any one of E62-E69, further comprising arranging theUV diffuse reflective layer and the flexible circuit such that at leastportions of the flexible circuit are positioned back-to-back, therebymaking a two-sided UV light generation system.

E71. The method of any one of E62-E70, further comprising arranging asecond UV light generation system adjacent to the UV light generationsystem such that at least a portion of the flexible circuit ispositioned adjacent to a portion of a second flexible circuit of thesecond UV light generation system, thereby making a two-sided UV lightgeneration system.

E72. The method of any one of E62-E71, further comprising positioning aUV diffuse reflective underlayer adjacent to the flexible circuit.

E73. The method of E72, further comprising applying an adhesive betweenthe UV diffuse reflective underlayer and the UV diffuse reflectivelayer.

E74. The method of E72, wherein the UV diffuse reflective underlayer isflexible.

E75. The method of any one of E62-E74, further comprising positioning anoverlayer adjacent to the UV diffuse reflective layer.

E76. The method of E75, wherein the overlayer is a UV transparentoverlayer, preferably having a UV transmission of at least 80% at 250nm.

E77. The method of E75, further comprising applying an adhesive betweenthe overlayer and the UV diffuse reflective layer, preferably whereinthe adhesive is a fluorinated ethylene propylene (FEP) adhesive.

E78. The method of E75, wherein the overlayer is flexible.

E79. The method of E75, wherein the overlayer comprises a photocatalyst,preferably a TiO2 surface coating or wherein the UV transparentoverlayer is attached to a TiO2 overlayer.

E80. The method of E75, further comprising applying a TiO2 surfacecoating to the overlayer or attaching a TiO2 further overlayer to theoverlayer.

E81. The method of E75, wherein the overlayer is a UV transmissivescattering overlayer.

E82. The method of any one of E62-E81, further comprising heating the UVdiffuse reflective layer.

E83. The method of any one of E62-E82, further comprising applyingpressure to the UV diffuse reflective layer.

E84. The method of E82, wherein heating the UV diffuse reflective layerincludes heating the UV diffuse reflective layer and an underlayer, anoverlayer, or both an underlayer or an overlayer.

E85. The method of any one of E62-E84, further comprising energizing themultiple UV-LEDs to generate UV light, wherein at least a portion of thegenerated UV light from the multiple UV-LEDs passes through thecorresponding openings in the UV diffuse reflective layer.

E86. The method of any one of E62-E85, further comprising wrapping theflexible circuit and the UV diffuse reflective layer around a mandrel.

E87. The method of E86, wherein wrapping includes helically,longitudinally, or circumferentially wrapping the flexible circuit andthe UV diffuse reflective layer around the mandrel.

E88. The method of E86, further comprising wrapping an underlayer aroundthe flexible circuit and the UV diffuse reflective layer.

E89. The method of E88, wherein the underlayer is a reinforcingunderlayer.

E90. The method of E88, wherein the underlayer is a UV diffusereflective underlayer.

E91. The method of E88, further comprising applying an adhesive betweenthe underlayer and the flexible circuit, preferably wherein the adhesiveis a fluorinated ethylene propylene (FEP) adhesive.

E92. The method of any one of E62-E91, further comprising wrapping anoverlayer around the mandrel, wherein wrapping the flexible circuit andthe UV diffuse reflective layer around the mandrel includes wrapping theflexible circuit and the UV diffuse reflective layer around theoverlayer and the mandrel.

E93. The method of any one of E62-E91, further comprising positioning atubular overlayer around the mandrel, wherein wrapping includes wrappingthe flexible circuit and the UV diffuse reflective layer around thetubular overlayer and the mandrel.

E94. The method of any one of E92 or E93, wherein the overlayer or thetubular overlayer is a UV transparent overlayer, preferably having a UVtransmission of at least 80% at 250 nm.

E95. The method of any one of E92 or E93, wherein the overlayer or thetubular overlayer is a UV transmissive scattering overlayer.

E96. The method of any one of E92 or E93, further comprising applying anadhesive between the UV diffuse reflective layer and the overlayer orthe tubular overlayer, preferably wherein the adhesive is a fluorinatedethylene propylene (FEP) adhesive.

E97. The method of any one of E62-E96, further comprising removing themandrel.

E98. An ultraviolet (UV) light generation system made by the method ofany one of E62-E97.

E99. An ultraviolet (UV) light generation system comprising: a flexiblecircuit including multiple ultraviolet light emitting diodes (UV-LEDs);and a UV diffuse reflective layer adjacent to the multiple UV-LEDs,wherein the UV diffuse reflective layer is flexible, wherein the UVdiffuse reflective layer includes multiple openings, and wherein eachUV-LED is positioned at a corresponding opening.

E100. The UV light generation system of E99, further comprising anoverlayer adjacent to the UV diffuse reflective layer.

E101. The UV light generation system of E100, wherein the overlayer is aUV transparent overlayer, preferably having a UV transmission of atleast 80% at 250 nm.

E102. The UV light generation system of E100, wherein the overlayer is aUV transmissive scattering overlayer.

E103. The UV light generation system of E100, wherein the overlayercomprises a photocatalyst, preferably a TiO2 surface coating or whereinthe UV transparent overlayer is attached to a TiO2 overlayer.

E104. The UV light generation system of E100, wherein the overlayercovers multiple openings in the UV diffuse reflective layer.

E105. The UV light generation system of E100, wherein the overlayer doesnot include UV absorbing filler material.

E106. The UV light generation system of E100, wherein the overlayer isUV stable.

E107. The UV light generation system of E100, wherein the overlayer isadhered to the UV diffuse reflective layer or laminated to the UVdiffuse reflective layer.

E108. The UV light generation system of any one of E99-E107, wherein theUV diffuse reflective layer is UV stable.

E109. The UV light generation system of any one of E99-E108, furthercomprising an underlayer positioned adjacent to the UV flexible circuit.

E110. The UV light generation system of E109, wherein the underlayer isa reinforcing underlayer.

E111. The UV light generation system of E109, wherein the underlayer isa UV diffuse reflective underlayer.

E112. The UV light generation system of any one of E99-E111, arranged todefine an enclosed region, wherein the multiple UV-LEDs are positionedto direct generated UV light into the enclosed region.

E113. The UV light generation system of E112, arranged to position atleast a first UV-LED of the multiple UV-LEDs in a configuration aboutthe enclosed region that is not directly opposed to any other of themultiple UV-LEDs.

E114. The UV light generation system of E112, wherein the enclosedregion corresponds to a fluid pathway.

E115. The UV light generation system of E113, wherein the UV lightgeneration system is arranged to form a tubular shape corresponding tothe fluid pathway.

E116. The UV light generation system of E113, wherein the UV lightgeneration system is wrapped helically, longitudinally, orcircumferentially around the fluid pathway.

E117. The UV light generation system of E113, wherein the fluid pathwaycorresponds to a liquid pathway and wherein exposing a liquid stream inthe liquid pathway to UV light generated by the multiple UV-LEDs reducesimpurities within the liquid stream or reduces impurities associatedwith particles suspended in the liquid stream.

E118. The UV light generation system of E113, wherein the fluid pathwaycorresponds to a gas pathway and wherein exposing a gas stream in thegas pathway to UV light generated by the multiple UV-LEDs reducesimpurities within the gas stream or reduces impurities associated withparticles suspended in the gas stream.

E119. The UV light generation system of E112, wherein at least twoportions of the UV light generation system are positioned to oppose oneanother and define the enclosed region.

E120. The UV light generation system of any one of E99-E119, arrangedalong an interior surface of a vessel, wherein the multiple UV-LEDs arepositioned to direct generated UV light into an interior of the vessel.

E121. The UV light generation system of any one of E99-E120, arrangedalong a surface of a structure positioned within a vessel, wherein themultiple UV-LEDs are positioned to direct generated UV light into aninterior of the vessel.

E122. The UV light generation system of any one of E99-E121, arrangedaround a central shaft, wherein the multiple UV-LEDs are positioned todirect generated UV away from the central shaft.

E123. The UV light generation system of E122, wherein the UV lightgeneration system is wrapped helically, longitudinally, orcircumferentially around the central shaft.

E124. The UV light generation system of E122, wherein the multipleUV-LEDs are positioned around the central shaft in a configuration togenerate a uniform UV emission field at a circumferential distance fromthe central shaft.

E125. The UV light generation system of any one of E99-E124, arranged asa two-sided sheet, wherein the multiple UV-LEDs are positioned to directgenerated UV light outward and away from the two-sided sheet.

E126. The UV light generation system of E125, wherein UV-LEDs positionedon a first side of the two-sided sheet do not back to any UV-LEDspositioned on a second side of the two-sided sheet.

E127. The UV light generation system of any one of E99-E126, wherein theflexible circuit further includes a UV sensitive photodetector, whereinthe UV sensitive photodetector is positioned at one of the multipleopenings of the UV diffuse reflective layer.

E128. The UV light generation system of any one of E99-E127, furthercomprising an adhesive layer for adhering two or more components of theUV light generation system to one another.

E129. The UV light generation system of E128, wherein the adhesive layeradheres an overlayer or an underlayer to other components of the UVlight generation system.

E130. The UV light generation system of E128, wherein the adhesive layercorresponds to a UV transparent layer.

E131. The UV light generation system of E128, wherein the adhesive layeris UV stable.

E132. The UV light generation system of any one of E99-E131, wherein theflexible circuit corresponds to a ribbon cable or a flat flexible cable.

E133. The UV light generation system of any one of E99-E132, whereineach of the multiple UV-LEDs are individually electrically addressable.

E134. The UV light generation system of any one of E99-E133, wherein atleast a portion of UV light generated by the multiple UV-LEDs isreflected by a UV diffuse reflective layer of the UV light generationsystem.

E135. The UV light generation system of any one of E99-E134, wherein themultiple UV-LEDs are positioned about the UV light generation system ina configuration to generate a uniform UV emission field at a distanceaway from the UV diffuse reflective layer.

E136. The UV light generation system of any one of E99-E135, includingone or more flat, concave, or convex sections.

E137. The UV light generation system of any one of E99-E136, wherein thearray corresponds to a regular array or a non-regular array.

E138. The UV light generation system of any one of E99-E137, wherein oneor more layers, underlayers, or overlayers of the UV light generationsystem are flexible or exhibit an elastic modulus of between 0.001 GPaand 3.0 GPa.

E139. The UV light generation system of any one of E99-E138, wherein oneor more layers, underlayers, or overlayers of the UV light generationsystem comprise polytetrafluoroethylene orexpanded-polytetrafluoroethylene (e-PTFE).

E140. The UV light generation system of any one of E99-E139 made by themethod of any one of E62-E98.

E141. The method of any one of E62-E98, wherein the UV light generationsystem comprises the UV light generation system of any one of E99-E139.

E142. A method of making an ultraviolet (UV) light generation system,the method comprising: wrapping a first UV diffuse reflective layer in afirst direction around a mandrel with a first gap between adjacentlongitudinal sides of the first UV diffuse reflective layer, wherein thefirst UV diffuse reflective layer is flexible; wrapping a second UVdiffuse reflective layer in a second direction around the mandrel andthe first UV diffuse reflective layer with a second gap between adjacentlongitudinal sides of the second UV diffuse reflective layer, whereinthe second UV diffuse reflective layer is flexible, and wherein aportion of the first gap and a portion of the second gap overlap togenerate a plurality of openings and positioning a flexible circuitincluding multiple UV-light emitting diodes (UV-LEDs) adjacent to thefirst UV diffuse reflective layer, wherein the positioning of theflexible circuit includes aligning the multiple UV-LEDs to correspond tothe plurality of openings.

E143. The method of E142, wherein each of the multiple UV-LEDs ispositioned to direct generated UV light through a corresponding opening.

Various modifications and additions can be made to the exemplaryembodiments of the disclosed treatment systems discussed withoutdeparting from the scope of the present invention. While the embodimentsdescribed above refer to particular features, the scope of thisinvention also includes embodiments having different combinations offeatures and embodiments that do not include all of the above describedfeatures. It will be appreciated that features of the variousembodiments and examples described herein may be combined with oneanother in any suitable combination and that the disclosed embodimentsare not limiting. For example, features in one embodiment may optionallybe imported into another embodiment if it is possible to do so.

1-61. (canceled)
 62. A method of making an ultraviolet (UV) lightgeneration system, the method comprising: generating a plurality ofopenings in a UV diffuse reflective layer, wherein the UV diffusereflective layer is flexible; and positioning a flexible circuitadjacent to the UV diffuse reflective layer, wherein the flexiblecircuit comprises multiple UV-light emitting diodes (UV-LEDs), andwherein the multiple UV-LEDs are aligned at corresponding openings ofthe plurality of openings in the UV diffuse reflective layer.
 63. Themethod of claim 62, wherein generating the plurality of openingscomprises removing portions of the UV diffuse reflective layer.
 64. Themethod of claim 62, further comprising generating the flexible circuit.65-68. (canceled)
 69. The method of claim 62, wherein the flexiblecircuit is a two-sided flexible circuit, wherein generating theplurality of openings in the UV diffuse reflective layer comprises:generating a first plurality of openings in a first UV diffusereflective layer; and generating a second plurality of openings in asecond UV diffuse reflective layer UV, and wherein positioning theflexible circuit comprises: aligning a first portion of the multipleUV-LEDs that are present on a second side of the two-sided flexiblecircuit with corresponding openings of the first UV diffuse reflectivelayer; and aligning a second portion of the multiple UV-LEDs that arepresent on a second side of the two-sided flexible circuit withcorresponding openings of the second UV diffuse reflective layer to forma two-sided UV light generation system.
 70. The method of claim 62,further comprising arranging the UV diffuse reflective layer and theflexible circuit such that at least portions of the flexible circuit arepositioned back-to-back to form a two-sided UV light generation system.71. The method of claim 62, further comprising arranging a second UVlight generation system adjacent to the UV light generation system suchthat at least a portion of the flexible circuit is positioned adjacentto a portion of a second flexible circuit of the second UV lightgeneration system to form a two-sided UV light generation system. 72.The method of claim 62, further comprising positioning a UV diffusereflective underlayer adjacent to the flexible circuit.
 73. The methodof claim 72, further comprising applying an adhesive between the UVdiffuse reflective underlayer and the UV diffuse reflective layer. 74.(canceled)
 75. The method of claim 62, further comprising positioning anoverlayer adjacent to the UV diffuse reflective layer.
 76. (canceled)77. The method of claim 75, further comprising applying an adhesivebetween the overlayer and the UV diffuse reflective layer. 78.(canceled)
 79. The method of claim 75, wherein the overlayer comprises aphotocatalyst or wherein the UV transparent overlayer is attached to aTiO2 overlayer.
 80. The method of claim 75, further comprising applyinga TiO2 surface coating to the overlayer or attaching a TiO2 furtheroverlayer to the overlayer. 81-85. (canceled)
 86. The method of claim62, further comprising wrapping the flexible circuit and the UV diffusereflective layer around a mandrel.
 87. (canceled)
 88. The method ofclaim 86, further comprising wrapping an underlayer around the flexiblecircuit and the UV diffuse reflective layer. 89-90. (canceled)
 91. Themethod of claim 88, further comprising applying an adhesive between theunderlayer and the flexible circuit.
 92. The method of claim 62, furthercomprising wrapping an overlayer around the mandrel, wherein wrappingthe flexible circuit and the UV diffuse reflective layer around themandrel comprises wrapping the flexible circuit and the UV diffusereflective layer around the overlayer and the mandrel.
 93. The method ofclaim 62, further comprising positioning a tubular overlayer around themandrel, wherein wrapping comprises wrapping the flexible circuit andthe UV diffuse reflective layer around the tubular overlayer and themandrel. 94-95. (canceled)
 96. The method of claim 92, furthercomprising applying an adhesive between the UV diffuse reflective layerand the overlayer or tubular overlayer.
 97. The method of claim 62,further comprising removing the mandrel.
 98. An ultraviolet (UV) lightgeneration system made by the method of claim
 62. 99-141. (canceled)